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La0.7Sr0.3MnO3 (LSMO)/poly(vinylidenefluoride-co-trifluoroethylene)(P(VDF-TrFE) particulate nanocomposite films prepared to produce large magnetoelectric (ME) voltage at room temperature for multifunctional device applications. LSMO nanoparticles (NPs) were prepared by sol–gel auto-combustion method and these NPs belong to space group R-3c. LSMO/P(VDF-TrFE) (0–3) nanocomposite (NC) films were prepared by solution casting method for different volume percentage of LSMO in P(VDF-TrFE). Dielectric and DC leakage current density(J) analysis of these NCs reveal very small loss tangents (~ 0.01) and very small leakage current density J ~ 10−7 A/mm2 respectively, which further demonstrate the uniform distribution of NPs in P(VDF-TrFE) matrix. Room temperature M-H and low temperature M-T analysis of LSMO NPs confirm ferromagnetic nature with Curie temperature at ~ 368 K. LSMO/P(VDF-TrFE) NC films exhibit multiferroic properties up to 5% volume percentage of LSMO at room temperature. A maximum ME voltage 11.68 mV is produced corresponding to giant transverse ME voltage coefficient ( $${\alpha }_{31}^{V})$$ = 155.74 mVOe−1 cm−1 at DC magnetic field (Hdc) = 2.57 kOe and AC magnetic fileld(Hac) = 25Oe for 0.5% LSMO volume percentage NC films. A self bias ME voltage 11.3175 mV is observed at zero Hdc for 0.5% LSMO volume percentage NC films, which can be used inpotential ME devices.The variation of ME voltage coefficient $$\left({\alpha }^{V}\right)$$ at different angles between P and applied magnetic field(Hdc) for 0.5% LSMO NC films is also reported which shows $${\alpha }^{V}$$ is maximum at the angles 90o and 270o.

A correlation between depolarization temperature, ergodicity and piezoelectricity of niobium-substituted (Na0.41K0.09Bi0.50)TiO3 has been investigated. The dielectric measurements display significant lowering of depolarization temperature and critical transition temperatures with increasing niobium content. The reduction in these characteristic temperatures has been attributed to disruption of long-range interaction between the oxygen octahedra with substitution of aliovalent niobium (+ 5) ion at the titanium (+ 4) sites. For compositions with niobium content less than 0.5 mol%, a reasonable increase (20–25%) in the piezoelectric coefficients has been observed. These coefficients decrease significantly for more niobium content more than 1.0 mol%. The results have been explained on the basis of dominance of donor-like behaviour of niobium ion at lower doping concentrations and emergence of ergodic relaxor phase due to lowering of depolarization temperature, for higher doping concentration. A structural phase diagram is proposed for niobium-doped (Na0.41K0.09 Bi0.5)TiO3.

Magnetoelectric (ME) coupling properties of La0.7Ba0.3MnO3 (LBMO)/P (VDF-TrFE) (0–3) nano-composite films were investigated for device-oriented application like magnetic sensors, actuators, energy harvesting devices etc., The LBMO nanoparticles were prepared by sol–gel auto combustion method. LBMO/P (VDF-TrFE) nanocomposite film was prepared by solution casting method for 0.5% volume fraction of LBMO nanoparticles in P (VDF-TrFE) matrix. This nanocomposite film shows ferromagnetic and ferroelectric properties simultaneously at room temperature. The ME properties of these composite films were studied extensively. The ME coupling coefficient is highly dependent on the angle between ferroelectric polarization and applied magnetic field. The maximum measured in plane ME voltage coefficient $$\left( {\alpha _{{31}}^{V} } \right)$$ is found to be 121.5 mV cm−1 Oe−1with application 25 Oe at 10 kHz by lock-in technique. The $$\alpha _{{31}}^{V}$$ is maximum at the angles 90° and 270° between ferroelectric polarization and applied magnetic field. The hysteresis of $$\alpha _{{31}}^{V}$$ confirms the existence of electric polarized domain formed with the decrease in magnetic field and the process is irreversible.

Undoped triglycine sulfate (TGS) crystals grown above and below its Curie temperature (Tc) along [010] polar direction by unidirectional solution growth method were characterized to measure and compare their device-relevant properties. The powder XRD was used for phase confirmation. The piezoelectric coefficient of TGS crystal grown below Tc was higher than that grown above Tc, and the P–E hysteresis studies show well-saturated hysteresis loops for both the crystals and the values of remnant polarization and coercive field were higher for crystal grown above Tc as compared to crystal grown below Tc. These observations were explained on the basis of the concentration of point defects and their influence on the domain nucleation and mobility. The crystal grown above Tc also exhibits higher dielectric permittivity, high mechanical hardness, low dislocations defects density, showing its improved device potential compared to TGS crystal grown below Tc. The probable reasons for the characterization results have been presented.

Magnetoelectric coupling of La0.7Ba0.3MnO3/ poly(vinylidenefluoride-co-trifluoroethylene) nano-composite (0–3) films were studied by varying the volume fraction of La0.7Ba0.3MnO3 in polymer matrix for non-poled and electrically poled conditions. The transverse magnetoelectric coupling coefficient (αV31) value is larger compared to αV33 (logitudinal coupling coeffcient) for composite films. The maximum value of αV31 is found to be 121.44 mVcm−1Oe−1 for poled composite films (0.5% La0.7Ba0.3MnO3 volume fraction) at 10 kHz. These films generate a self-biased voltage 9.1 mV on application of 25Oe alternating magnetic field (Hac). The dependence of αV31 of these films on static magnetic field (Hdc), Hac and frequency is also reported.

Pure and 0.1 mol% Xylenol orange (XO) doped Imidazolium L-tartrate (IMLT) nonlinear optical (NLO) single crystals were grown using Sankaranarayanan–Ramasamy (SR) method of uniaxial solution crystallization technique. The pure IMLT crystal is 100 mm in length and 15 mm in diameter. The doped IMLT crystal is 25 mm in length and 10 mm in diameter. UV–Vis-NIR spectrum shows that the pure and XO doped IMLT crystals' cut off wavelength is 235 nm. High-resolution X-ray diffraction (HRXRD) measurement and birefringence interferometry confirm that the SR method grown crystal has good crystalline perfection and optical homogeneity. The wavelength dependent refractive index and piezoelectric d33 coefficient were measured. The difference refractive index (Δn) of (100) plane in parallel and perpendicular directions shows a strong dependence on wavelength. The dielectric constant, hardness and SHG conversion efficiency were also increased as a result of XO dye doping in IMLT crystal.

Nano-particles of GdFeO3 (GFO) and Gd0.4Sm0.6FeO3 (GSFO) were synthesized by sol-gel auto-combustion method to study the effect of Sm3+doping on physical properties of GFO. Rietveld refinement of x-ray diffraction pattern confirms the proper phase formation of samples and the average octahedral angle of GSFO is found to be 145.54⁰ which is larger compared to GFO 142.53⁰. Temperature dependent DC magnetization measurements showed that Sm doping in GdFeO3introduces spin-reorientation transition which is absent in pure GdFeO3 phase. The dielectric constant of GSFO is found to be larger than that of GFO because of change in hybridization between the O-2p states and Fe-3d states. In both the ceramics at higher temperatures (above 150 °C) conduction mechanism is taking place via oxygen defect charge carrier hoping. The complex impedance analysis revealed that the distribution of relaxation time of charge carriers is temperature independent. Sm doping in GFO not only changed the dielectric properties but also changed the magnetic coercive field and shape of the magnetic isotherm of GFO.

In this study, we investigate magnetoelectric (ME) properties in nanocomposite films (P(VDF-TrFe))/SmFeO3 consist of ferroelectric copolymer, poly(vinylindene fluoride-trifluoroethylene) (P(VDF-TrFe)) and magnetic SmFeO3 nanoparticles. Comparative magnetization vs magnetic field hysteresis loops for un-poled and electric field poled (P(VDF-TrFe))/SmFeO3 nanocomposite films demonstrate strong electric filed control of magnetization. The nanocomposite films exhibit large exchange biasing (EB) effects in magnetic measurements near spin switching temperature (~ 100 K) of SmFeO3 and the EB effects were significantly modified under electric field (E) poled conditions (at E = 200 kV/cm), indicating ME coupling. Remarkably, we observe electric field poling induced self biased converse ME effect in the (P(VDF-TrFe))/SmFeO3 nanocomposite films. The maximum magnetoelectric output voltage (α) obtained is 55 mV/cm/Oe at Hbias = 1 kOe and 25 mV/cm/Oe at Hbias = 0, after electric field poling. The discovery of self biasing phenomenon with converse ME effects at room temperature in flexible (P(VDF-TrFe))/SmFeO3 nanocomposite films is highly desirable for device applications such as electrically controlled thin memory devices and ME sensors etc.

Neodymium doped transparent yttrium aluminum garnet ceramics with yttrium excess and deficient (1 to 3 mol%) compositions were fabricated. The samples with stoichiometric and 1.0 mol% yttrium excess are transparent. However, 1.0 mol% yttrium deficiency samples are opaque. The structural and compositional analysis corroborates the presence of alumina as secondary phase for yttrium deficient compositions and yttrium aluminum perovskite for yttrium excess compositions. It is found that yttrium deficiency is highly detrimental to the transparency as compared to yttrium excess. The solubility width of garnet phase is found to be lower than 1.0 mol% for yttrium excess and deficiency.

GdVO4 single crystals doped with different concentration of Nd (0.6, 0.8, 1.0 and 1.2 at.%) were grown by optical floating zone method. The absorption coefficient measured for two orthogonal polarization of light is different due to anisotropic structure in both the direction. The line strength and Judd-Ofelt parameters evaluated from the recorded absorption spectra are also dependent on the polarization of the incident light. Further, the spectroscopic quality factor was estimated by Judd Ofelt parameters and found to be maximum for 0.8 at.% Nd doped GdVO4 crystals. The emission study shows that photoluminescence (PL) intensity at 1062 (lasing wavelength), 1069 and 1081 nm increases with the doping concentration of Nd up to 0.8 at.% and beyond that the PL intensity at all emission wavelengths decreases. The emission cross-section with excitation at 808 nm was estimated by Judd Ofelt theory for the 4F3/2 → 4I11/2 transition and it was found to be independent of doping of Nd in GdVO4. The measured fluorescence life-time of Nd:GdVO4 samples is ∼100, 101, 92 and 93 μs corresponding to the doping concentration of 0.6, 0.8, 1.0 and 1.2 at.% of Nd respectively. The measured fluorescence life-time exhibits the maximum value for 0.8 at.% of Nd doping. The decrease in the PL intensity as well as fluorescence life-time for higher doping concentration is because of quenching due to ion-to-ion interaction in the crystal. All the spectroscopic investigation presented here suggest that the optimum concentration of Nd ion in GdVO4 single crystals is 0.8 at.%, at which the best lasing performance can be obtained.

The mechanical properties of undoped and 2.0, 4.0 and 6.0 mol% Mg-doped LN single crystals, grown by the Czochralski technique, have been investigated using nanoindentation studies to understand the mechanical deformation behaviour as doping is increased. This has been correlated with structural investigations by powder XRD analysis and Raman spectroscopy. Powder X-ray diffraction measurements show a slight increase in the lattice parameters as the Mg content is increased in the crystal. The lattice strain developed due to the doping has been calculated by the Williamson-Hall relation. The influence of Mg incorporation on lattice vibrations was analysed using Raman spectroscopy, which indicated no shift in the peak positions with doping, and only slight variation in the intensity and width of the peaks. The grown crystals were subjected to nanoindentation and the Young's modulus and hardness values were obtained by using the Oliver-Pharr method. The results reveal the optimal doping levels of Mg which result in enhanced mechanical strength of lithium niobate single crystals.

Lithium Niobate (LiNbO3; LN) nanoparticles were dispersed into a polymer matrix, poly(methyl methacrylate) (PMMA) to prepare an organic–inorganic hybrid LN/PMMA nanocomposites. When no electric field was applied during dispersion, the polar LN nanoparticles remain randomly oriented in the PMMA and unpoled nanocomposite is obtained. In this work, poled LN/PMMA nanocomposites were prepared by applying an electric field of varying strength and used to investigate its influence on the second harmonic generation (SHG) properties (λ = 532 nm) using the fundamental laser (λ = 1064 nm). Since the electric field orients the dipoles of the LN nanoparticles inside the PMMA matrix in the direction of the field, a maximum was observed in the SHG signal as a function of electric field strength. The SHG from the differently poled nanocomposite was investigated as a function of LN nanoparticle concentration, fundamental laser energy, and sample thickness. The trend in SHG is explained and the role of induced and spontaneous polarizations in the SHG generation has been specifically highlighted. It has been observed that the effect of electric field on the SHG properties of the nanocomposite was observed only when the factors contributing to the loss of SHG signal are insignificant.

An organic–inorganic nanocomposite (LN/PMMA) was prepared using nearly stoichiometric lithium niobate (LiNbO3; LN) nanoparticles dispersed homogeneously into a polymer matrix, poly(methyl methacrylate) (PMMA). This composite is having anisotropic LN nanocrystals, oriented randomly in an isotropic host matrix of PMMA. So far, to the best of our knowledge, different nonlinear optical (NLO) properties have been studied for organic–inorganic nanocomposites in thin film and waveguide form, the thickness of which was in micron and submicron order. In this article, for the first time, we have presented SHG properties of thick LN/PMMA nanocomposites of thickness, 0.1 mm and above. LN/PMMA nanocomposite samples of different thickness and different concentrations of LN nanoparticles were fabricated. The attenuation coefficients of these samples, measured at laser wavelengths of 1064 nm and 532 nm, show a deviation from Beer-Lambert law. In the LN/PMMA nanocomposite, the effect of the randomly oriented LN nanoparticles on second harmonic generation (SHG) has been studied as a function of (a) input pulse energy of the fundamental laser (1064 nm), (b) LN nanoparticle concentration and (c) the sample thickness. The net effect was found to be the result of two competitive phenomena; harmonic generation and different losses from LN nanoparticles. Thermal effects at high input pulse energy also play important role in second harmonic generation. Through these studies, one can get an idea about the collective behavior of LN nanoparticles, particularly effect on their linear and nonlinear optical properties, and how they can be dispersed in isotropic host matrices (to different concentration levels) to achieve the desired NLO effect.

Optically transparent, urea (5 wt%)-doped triglycine sulphate (Ur-TGS) single crystals were grown along polar axis [010] by Sankaranarayanan–Ramasamy unidirectional solution growth method, below and above its Curie temperature Tc = 49.3 °C. Higher growth rate of 5 mm/day was obtained for Ur-TGS crystal grown above Tc. The phase of the grown crystals was confirmed by powder XRD. P–E hysteresis studies show well-saturated hysteresis loop for crystal grown below Tc, and the remnant polarization was 0.60 µC/cm2 with a coercive field of 1.5 kV/cm. The piezoelectric d33 coefficient for Ur-TGS crystal grown below and above Tc was 25 pC/N and 35 pC/N, indicating improved piezoelectric properties of the latter. Dielectric permittivity for Ur-TGS crystal grown above Tc was approximately 10 times higher as compared to the crystal grown below Tc. Improved Vickers microhardness and lower Meyer’s index (n) were observed for Ur-TGS crystal grown above Tc. The etch pit density (EPD) of Ur-TGS crystal grown below and above Tc was 1.8 and 1.1 × 102 dislocations/cm2, respectively, indicating that the quality of the crystals grown above Tc was better than the crystal grown below Tc. The optical transmittance of Ur-TGS crystal grown above Tc was slightly (~ 5%) more than that of crystal grown below Tc. Overall, it is concluded that the higher growth rate and improved physical properties of Ur-TGS crystal grown above its Curie temperature show its suitability for the ferroelectric device applications.

The organic nonlinear optical (NLO)2-aminopyridinium 4-nitrophenolate 4-nitrophenol (2AP4N) single crystals were successfully grown by point seed rotation technique and novel Rotational Sankaranarayanan-Ramasamy (RSR) method. The unit cell parameters of the 2AP4Nsingle crystals were confirmed by single crystal X-ray diffraction (SXRD) analysis. The crystalline phase purity anddirection of RSR method grown crystal were confirmed by powder XRD (PXRD) measurement. The optical qualityof the 2AP4N crystal wasanalyzed by UV-Vis NIR spectrum analysis. TheKurtz–Perry powder technique was used to find the second harmonic generation (SHG) efficiency of the 2AP4N crystal using Nd:YAGlaser at the wavelength of 1064 nm. The SHG efficiency was found to be 4.5 times that of KDP. Refractive index measurement was carried out with different wavelength using prism coupling method. The phase matching angle of 2AP4N was find out by fitting Sellmeier equation. Based on the phase matching angle, the grown 2AP4N crystal wascut and the type-I and type-II SHG elements were fabricated.

SmFeO3 a member of ReFeO3 (Re stands for rare earth) family has highest spin reorientation temperature (∼ 450 - 480 K) which makes them very useful for Spintronics application. Nano particles of Sm0.3Er0.7FeO3 has been synthesized by sol-gel auto-combustion method to study the effect of Er3+doping on spin reorientation of SmFeO3. Rietveld refinement of the X-ray diffraction pattern revealed that the average octahedral (FeO6) tilting of Sm0.3Er0.7FeO3 ( =18.44□) was increased as compare to SmFeO3 ( =14.42□). TEM image shows the average particle size is of the order of 50-80 nm. Temperature dependent DC magnetization measurement shows, that the Er doping in SmFeO3 resulted in the shifting of its spin reorientation temperature (Tsr) at 140 - 160 K from that of 450 -480 K of SmFeO3. The M-H measurements at 300 K show weak ferromagnetic behavior while paramagnetic behavior at 10 K. Hence, it is shown that by doping of Er in SmFeO3, the Tsr can be modified.

The good quality and bulk size organic nonlinear optical 4-aminopyridinium 4-nitrophenolate 4-nitrophenol (4AP4N) single crystals were grown by slow evaporation solution technique (SEST) using methanol as a solvent. The lattice parameters of the grown crystal were analyzed by single crystal X-ray diffraction (SXRD) analysis. The optical quality of the grown crystal was analyzed by UV-Vis NIR spectral analysis. The photoconductivity studies revealed that the 4AP4N crystal has negative photoconductivity nature. The laser damage threshold (LDT) was studied for the 4AP4N crystal by using Nd: YAG laser (532 nm). The second harmonic generation (SHG) efficiency of 4AP4N crystal was studied by Kurtz-Perry powder technique.

High specific surface area carbon aerogels are being studied for various electrochemical applications. Their utility in these applications is limited due to moderate electrical conductivity. The current manuscript briefs about the effect of high temperature (HT) treatment (-1400 °C) on the conductivity and surface properties of resorcinol-formaldehyde (R-F) based carbon aerogels. Aqueous medium based carbon aerogel with high specific surface area (1796 m2/g) was synthesized by R-F gelation, ambient drying followed by CO2 activation treatment. The samples of carbon aerogel with HT treatment (CA-HT) were characterized for textural properties, conductivity, X-ray diffraction and specific capacitance. The specific surface area of CA-HT (1742 m2/g) showed only marginal decrease after HT treatment mainly due to partial collapse of micropores. The bulk electrical conductivity of CA-HT showed ∼ 35% improvement over the untreated CA with respective values of 165 S/m and 115 S/m. The specific capacitance for both CA and CA-HT were evaluated nearly ∼ 112 F/g at scan rate of 10 mV/s. For higher scan rate 100 mV/s, the CA showed drastic decrease in specific capacitance to 74 F/g, however, for CA-HT the value decreased only to 92 F/g. Equivalent series resistance (ESR), a crucial electrochemical parameter, improved to 0.5 n after HT treatment. The higher specific capacitance at faster scan rates and lower ESR for CA-HT is attributed to improvement in bulk conductivity which makes it a better choice for supercapacitor application.

Magnetoelectric coupling of La0.7Ba0.3MnO3/ poly(vinylidenefluoride-co-trifluoroethylene) nano-composite (0-3) films were studied by varying the volume fraction of La0.7Ba0.3MnO3 in polymer matrix for both non-poled and electrically poled conditions. The transverse magnetoelectric coupling-coefficient (αV31) value is larger compared to αV33 (logitudinal coupling-coeffcient) for both non-poled and electrically poled films. Poled composite films are showing highest αV31 = 121.44 mV/Oe-cm at 10 kHz for 0.5% volume fraction of La0.7Ba0.3MnO3. These films generate self-biased voltage 9.1 mV on application of 25Oe alternating magnetic field (Hac). The dependence of αV31 on static magnetic field (Hdc), Hac and frequency for these films is also reported.

A non-critical point drying method of carbon aerogel synthesis using high temperature sol-gel process of resorcinol and furfuraldehyde (R-F) in isopropyl alcohol medium is reported in this paper. The R-F gelation was performed at a temperature of ∼130°C, which is much above the routine gelation temperatures followed by drying under ambient conditions and pyrolysis. Further activation of the aerogel under CO2 atmosphere at 920°C resulted in significant enhancement in its surface area and prominently mesopore dominated carbon aerogel was obtained. The carbon aerogel (CA) was evaluated to have specific surface area 698 m2/g with high mesopore area of 425 m2/g. The surface area properties of the CA prepared by the modified method compare well with the CA by critical point drying technique which is cumbersome, expensive and time consuming. XRD studies showed graphitic nature of this CA which was supported by SEM imaging displaying layered morphology. The high electrical conductivity of 190 S/m obtained for this CA is attributed to its graphitic layered structure. The enhanced conductivity and high mesoporosity makes this CA variant a good alternative as base matrix for catalyst and electrochemical applications.

The new organic nonlinear optical (NLO)single crystalsof quinoline 4-nitrophenol (QNP)were successfully grown by slow evaporation solution technique (SEST) using methanol as solvent. The crystal structure was confirmed by single crystal X-ray diffraction (SXRD) analysis. The crystalline planes and phase purity were analyzed by powder XRD (PXRD) measurement. The optical quality andband gapenergyof the grown crystal were obtained by UV-Vis NIR spectrum analysis. The QNP crystal was subjected to photoluminescence (PL) analysis and the maximum emission was found at 450 nm. The chemical etching study was carried out and confirms that the QNP crystal has less dislocation density. The third-order nonlinear optical properties such as refractive index (n2), absorption coefficient (β) and susceptibility (χ(3)) were studied using Z-scan technique at 632.8 nm with a continuous wave (CW) laser.

Nd doped GdVO4 crystals were grown by optical floating zone technique. The crystalline quality was checked by rocking curve. The Full width half maxima (FWHM) of (200) diffraction peak is ∼54 arc second. From the grown Nd (0.6 at.%) doped GdVO4 single crystals ‘a’-cut laser elements of dimension 4x4x6 mm3 were fabricated. To fabricate the elements the grown crystal was oriented using the Laue diffraction pattern recorded in the reflection geometry. Further, the anti-reflection coating on the laser element was done to reduce the losses inside the laser cavity. The testing of lasing for a-oriented element carried out using plane-plane resonator geometry with 808 nm pumping. CW laser emission at 1064 nm was demonstrated. The laser output power of 4.57 W at 1064 nm was achieved for 11.94 W of incident pump power with a slope efficiency of ∼49.7%.

Single crystals of glycine-di-glycinium sulphate (TGS) have been synthesized and grown along direction. The crystals were subjected to gamma irradiation with dosage ranging 10-50 kGy. While observing the low temperature Raman scattering modes, it can be understood that there exists possible bond breaking mechanisms upon gamma irradiation and as its consequence free radical ions appeared to have been formed. Thermo-mechanical parameters such as linear thermal strain, thermal expansion and linear thermal expansion coefficient have been computed by performing thermo-mechanical analysis on the irradiated samples. Gamma irradiation induced crystal imperfections were assessed through the high resolution XRD (HRXRD) measurement and it provides a clue for the development of non-uniform strain in the crystal. Modulation in optical constants, on irradiation was also noticed from the refractive index measurements. Piezoelectric and ac- conductivity measurements confirmed the rupture of bonds and in turn causing deterioration of ferroelectric and piezoelectric properties of the irradiated crystal.

The SmFeO3, a family member of rare earth orthoferrite, is a potential candidate for future industrial (spintronics) applications due to highest spin reorientation temperature (453-483 K) among other RFeO3 members. There are ambiguous reports on high permittivity behavior of SmFeO3. In this report, the origin of high permittivity in SmFeO3 is attributed to microstructure rather than inherent material property of material. Ceramic pellets of SmFeO3 were prepared in two different routes i. e. solid-state route and nano-combustion synthesis route. The dielectric and conductivity properties of these pellets were studied as function of frequency as well as temperature. Impedance spectroscopy was used to study the dielectric and resistive behavior of SmFeO3. The central findings of this work are; (i) the high dielectric constant of SmFeO3 is not an inherent material property instead strongly dependent on microstructure and preparation conditions and (ii) the anomalous behavior in dielectric, conductivity and impedance observed at spin reorientation temperature regime of SmFeO3 is attributed to strong magneto dielectric coupling in SmFeO3.

Single crystals of 0.7 at% Er:YVO4 co-doped with varied concentrations of Yb (1.5, 3.0 and 8.0 at%) were grown by optical floating zone technique. The absorption spectra of the grown crystal are characterized by the prominent absorption at 985 nm due to Yb ion and multiple absorption due to Er ions. The overall characteristic absorption for π-polarization (E||c) is stronger than that for σ-polarization (E┴c) due to alignment of dipole moments along c-direction. The line strength of all the transitions of Er ions decreases as the doping concentration of Yb increases. Judd Ofelt parameter Ω2, which strongly depends on the environment of ligand, decreases with increasing Yb concentration in the lattice. The value of spectroscopic quality factor was found to be nearly invariant (~ 1.80) with respect to the Yb doping concentration but better than that for Er doped YVO4 (~1.31) [1] . The radiative lifetime and emission cross-section of 4I13/2→4I15/2 transition of Er ions was also found to be independent of Yb doping concentration. This is one of the biggest advantages of Yb co-dopant as a good sensitizer in the Er:YVO4 as it results in high population density in upper level of Er ions making it. The emission cross-section of 4I13/2→4I15/2 line for excitation at 985 nm is ~ 2.33 × 10−20 cm2. Further, the values of emission cross-section for both the excitation at 808 nm (Er absorption line) and 985 nm (Yb absorption line) were found nearly same.

Utilization of magnetoelectric effects in multiferroic materials hold great potential to fabricate nonvolatile memory devices with outstanding characteristics. In particular, organic thin memories are favorable because of their environment friendly nature, mechanical flexibility, and low fabrication cost. In this work, we have demonstrated a room temperature paradigm two level nonvolatile memory operation by exploiting the nonlinear magnetoelectric effects in flexible SmFeO3/P(VDF-TrFE) nanocomposite films using organic ferroelectric polymer (P(VDF-TrFE)) as a host matrix. Strong strain mediated interfacial interactions between ferromagnetic and ferroelectric phases in SmFeO3/P(VDF-TrFE) nanocomposite films allow electric field controlled magnetic switching. The maximum magnetoelectric coefficient (α) obtained is 45 mV cm–1 Oe1– at Hbias= 1 kOe and 16 mV cm–1 Oe1– at Hbias= 0 in electrically poled composite films (30% SmFeO3). The experiments demonstrate that during seven operative cycles for 1500 s, the ...

Polycrystalline samples of Pb1-xLax/2Smx/2Ti1-xFexO3 (x = 0.20 and 0.30) have been prepared by solid state reaction route. The electrical properties of synthesized samples have been investigated using complex impedance spectroscopy as a function of frequency (100 Hz–1 MHz) within the temperature range of (448–573 K). The fitting of the Nyquist plots reveals that both grain and grain boundary contribute to relaxation and the grain boundaries are more resistive and capacitive than the grains. Modulus analysis shows that relaxation in both the samples is of non-Debye type and temperature independent. The Jonscher`s power law fit to the ac conductivity data confirms that the conduction in the prepared samples is due to the hopping of charge carriers. Long range conductivity type of relaxation is found in both the samples.

Single phase PLZT (7/65/35) ceramics doped with Cr2O3 [0,0.05, 0.08, 0.18, 0.30 0.50, 0.75 and 1.0 wt%] were synthesized by high temperature solid-state reaction technique accompanied by hot pressing. XRD studies revealed that the chromium doping reduces the lattice parameter of PLZT (7/65/35) without changing its crystal structure. A relaxor like behavior with decrease in temperature of dielectric constant maxima (Tm) was observed with increase in chromium content. A sharp rise in the conductive losses were observed for higher chromium (≥0.08 wt%) contents. The room temperature dielectric constant (e′RT) and electromechanical coupling coefficient (k31) showed maxima value for 0.08 wt% Cr2O3 doped PLZT (7/65/35) ceramic. The results were interpreted on the basis of multiple valence nature of chromium.

Single crystals of Cr co-doped Nd (0.5 at%):GdVO4 with varied Cr concentrations of 1.0, 1.2 and 1.5 at% were grown in ambience having 10%, 20% and 25% oxygen by optical floating zone technique for the first time to the best of our knowledge. Lattice parameters were found to be unchanged with Cr doping concentration. The etch pit dislocation density was in the range of 103–104/cm2. The observed fringes of nearly uniform thickness and spacing in birefringence interferometry indicate the optical uniformity of the crystal across the cross-section. Further, the effect of the doping concentration and the growth atmosphere on the optical absorption, particularly for the 2A1→2B2 transition (at ~1100 nm) due to Cr5+ ion, was investigated using polarized lights (i.e., E ǁ [001] or π-polarized) and E ⊥ [001] or σ-polarized) and found to be polarization sensitive. The transition peak of Cr at 1100 nm are allowed only for π- polarization of light whereas the transitions at 650 nm are allowed only for σ- polarization of light. The absorption of Cr5+ ion increases at 1100 nm with the increase of oxygen ambience for the Cr concentration 1.2 and 1.5 at% and for the crystals with Cr concentrations of 1.0 at%, a reverse effect in the absorption of Cr5+ ion was observed. The broad absorption transition at ~1100 nm is important as it results in saturable absorption that is used for self-Q-switching application. In accordance with the absorption data the photo luminescence intensity increases for 1.0 at% Cr doping and decreases for the 1.2 and 1.5 at% Cr doping with the increase of oxygen percentage in the growth ambience respectively. The observation has important technical implication in context to saturable absorption application. It suggests that to attain the desired level of saturable absorption, the growth ambience and the concentration of Cr should be chosen in line with the result presented here.

This paper presents the magneto-structural study on orthoferrite TmFeO3 and Sm substituted TmFeO3 across spin reorientation transition (SRT) temperature. A strong change in magnetic anisotropy due to the substitution of the Sm3+was observed, which is reflected as a change in spin reorientation transition (SRT) temperature. The SRT temperature of Tm0.5Sm0.5FeO3is found to be around 200–230 K, which is relatively high in comparison to TmFeO3. A sudden decrease in the value of coercivity has been observed in the SRT region for both the sample. The lattice dynamics of TmFeO3 and Tm0.5Sm0.5FeO3were investigated by temperature-dependent x-ray diffraction and Raman spectroscopy. We observed unusual contractions in the lattice parameter at low temperatures due to complex exchange interaction between RE3+ and Fe3+ ions sub-lattice. Anomalous behavior in lattice parameters was observed in the vicinity of SRT, which confirms the system’s spontaneous magnetostriction.The strong anomaly was observed in line width and phonon frequency of Raman modes of around SRT, which established the spin-lattice coupling in TmFeO3 and Tm0.5Sm0.5FeO3 nanoparticles. Observation of spin-lattice coupling utilizing Raman scattering substantiates our magnetic and structural correlation and supports its candidature for magneto-elastic applications.

Imidazolium L -tartrate (IMLT) single crystal has been grown by slow cooling seed rotation technique. The temperature dependent refractive index (RI) has been measured along the principal axes in the temperature range 30–125 °C. The prism coupling technique has been used to determine the refractive index with accuracy ~ 5 × 10−4. The transmission spectra depict good transparency in the range 340–1350 nm. The principal axes directions have been identified using polarized light microscopy. Principal directions have been found rotated by 44° in the orthogonal xz-plane with respect to the crystallographic x-axis. The generalized temperature dependent equations for the Sellmeier’s and thermo-optic (dn/dT) coefficients have been determined. The thermo-optic coefficients (TOC) in the above-specified range have been found to be negative and are ~10−5/°C. An important set of empirical relations between TOC and wavelength (407–1551 nm) has also been established which is useful for estimating TOC in the temperature range of 30–125 °C. Based on the birefringent measurement it has been confirmed that the IMLT crystal is a negative biaxial crystal.

Transparent Nd doped PLZT ceramic was fabricated using uni-axial hot press. Spectroscopic investigation of Nd 3+ (1.0 at%) doped PLZT(8/65/35) ceramic was carried out using Judd–Ofelt theory. Based on this theory the calculated intensity parameters are; Ω 2 = 2.22 × 10 –20 cm 2 , Ω 4 = 1.31 × 10 −20 cm 2 , Ω 6 = 2.32 × 10 –20 cm 2 . These intensity parameters are used to determine the emission probabilities, radiative lifetimes, and branching ratios of the 4 F 3/2 → 4 I J ( J = 9/2, 11/2, 13/2, 15/2) transitions. The calculated radiative lifetime (179 μs) is in good agreement with the measured life time (166 μs). Finally, the emission cross-section of the potential laser transitions was also evaluated.

In this study, we present first ever fabrication of Er/Dy co-doped Y 2 O 3 transparent ceramic and demonstration of energy transfer upconversion mechanism between Dy 3+ and Er 3+ . The spherical nanoparticles of Er/Dy co-doped Y 2 O 3 were synthesized by coprecipitation technique and transparent ceramics were fabricated by vacuum sintering of nanoparticles at 1750 °C for 5 h. A transmittance of ~ 80% (in ~ 600–2000 nm range) without Fresnel loss correction was achieved by substituting sintering aids like Zirconium and Lanthanum during preparation of nano particles without affecting the cubic phase of Er/Dy co-doped Y 2 O 3 . The upconversion luminescence spectra in visible region have been studied. The measured excitation spectrum gave evidence of the energy transfer from Dy 3+ to Er 3+ energy levels. The Judd–Ofelt intensity parameters, spontaneous emission rate, branching ratios and radiative emission lifetimes corresponding to transition wavelengths of Er 3+ were determined. The observed strong emission band at 564 nm (Er 3+ : 4 S 3/2 → 4 I 15/2 ) under 1077 nm (Dy 3+ : 6 H 15/2 → 6 F 9/2 ) excitation prove its potential as a promising gain medium for compact solid-state upconversion laser.

Controlling the magnetic properties of a material is of great importance for spintronics and magnetoelastic devices. We studied effect of reduced particle size on structural, dielectric and magnetic properties of SmFeO3 nanoparticles prepared by co-precipitation method (SFO-C) and by combustion (SFO-S). Reduced particle size modified interesting magnetic features of SmFeO3. Temperature dependent magnetic study reveal significant enhancement in magnetization reversal temperature and drop in spin reorientation transition temperature. The signature of spin reorientation transition for SFO-C (~ 300 nm) is marked at ~ 450 K, while this temperature drops down to ~ 400 K for SFO-C (~ 50 nm). The magnetization reversal temperature is achieved at 30.5 K for SFO-C, much higher than 4 K, reported for the single crystal and bulk SmFeO3. The presence significant anomalies in the temperature dependent dielectric behavior of SmFeO3 samples across spin reorientation transition temperature indicate magneto electrical coupling. Strong exchange–bias effect is observed at low temperature for both the samples. The lowering of spin reorientation/switching transition temperature due to reduction in particle size and the signature of magnetoelectric coupling at this temperature are useful for room temperature devices. The observed experimental results establish that the spin switching properties of SmFeO3 can be modified for practical applications in devices.

Cerium doped transparent YAG ceramics 0.15–2 at% cerium) were prepared using nano-powder technique and vacuum sintering. The effective solubility limit of cerium in YAG was found to lie between 1.0 and 1.5 at%. The PL intensity increases with the cerium content and attains a maximum for 1.0 at% doping. Lifetime of PL is not very sensitive to cerium content, however, a slight decrease in the life-time from 66 ns to 55 ns was observed with increase in cerium content from 0.15 to 2.0 at%. This decrease in PL intensity and life-time is attributed to concentration quenching for the YAG ceramics with cerium content higher than 1.0 at%. A red-shift in the PL peak position was observed and attributed to the local symmetry distortion in YAG matrix.

$$\upalpha $$ - $$\hbox {LiIO}_{3}$$ is an excellent optical material exhibiting strong nonlinear optical, piezoelectric and elasto-optic properties. However, its practical applications are limited by the insufficient reproducibility of the mentioned properties caused by the strong influence of the growth conditions, and, in particular, pH of the solution from which $$\upalpha $$ - $$\hbox {LiIO}_{3}$$ crystal is grown. Herein, we investigate to grow bulk size good quality crystals of $$\upalpha $$ - $$\hbox {LiIO}_{3}$$ based on the observed problems during its crystallization process. A systematic investigation was carried out to find the effect of pH on solubility, crystal growth, structural, surface and laser damage properties of $$\upalpha $$ - $$\hbox {LiIO}_{3}$$ single crystals. The structure and phase of $$\hbox {LiIO}_{3}$$ were confirmed by powder X-ray diffractometer analysis. The functional groups of the compound were identified using Fourier transform infrared spectroscopy. Surface defects of the grown crystals were studied by etch patterns. The crystal grown at pH 10 showed 10% optical transmission enhancement in comparison to the crystals grown at pH 2. The indirect optical bandgap of the crystal was reinvestigated using ultraviolet–Visible–near-infrared transmittance spectrum. The laser damage threshold studies of the crystals grown at pH 10 reveal the higher optical radiation stability against 532 nm laser. The second-order nonlinear optical behaviour of $$\upalpha $$ - $$\hbox {LiIO}_{3}$$ crystals grown at different pH conditions have been investigated by using Kurtz and Perry powder technique with Nd:YAG laser pulses at the wavelength of 1064 nm.

We report the fabrication of transparent (Yb0.01Zr0.02La0.01Y0.96)2O3 ceramic pellets by vacuum sintering of non-agglomerated spherical nanoparticles which were prepared by co-precipitation method. The co-doping of La3+ and Zr4+ in Yb:Y2O3 enhanced the transparency of sintered ceramic pellet. The inline transparency of (Yb0.01Zr0.02La0.01Y0.96)2O3 ceramic pellets improved to ~80% at lasing wavelength (1030 nm) which is comparable to theoretical transmittance for Y2O3 (without Fresnel correction). The dopants in Yb:Y2O3 did not change the spherical nature of nanoparticles but changed the particle size distribution. The cross-sectional SEM images confirmed the effect of dopant on reduction of pores and merger of grains of La3+ and Zr4+ doped transparent Yb:Y2O3 ceramic pellet. The dopants didn’t affect the emission and absorption wavelength of transparent Yb:Y2O3 ceramic pellet. The absorption cross section at 906, 951 and 976 nm excitations are found to be 1.97 × 10−20, 2.27 × 10−20 and 3.59 × 10−20 cm2 respectively.

Bulk size pyroelectric undoped and Cd- and Mn-doped lithium sulfate monohydrate (LSMH) single crystals were successfully grown along the polar axis by the unidirectional crystal growth method. The influence of transition metal ions (Cd and Mn) on crystal growth and the linear/nonlinear optical, pyroelectric, and piezoelectric properties of the LSMH crystal were studied. The crystalline perfection of the grown crystals was assessed using a rocking curve of the HRXRD pattern. The vibrational spectroscopic properties of undoped and doped single crystals were analyzed using micro-Raman scattering measurements on the 〈010〉-oriented crystal surface. The optical quality was assessed by recording the UV-Vis-NIR transmission on the different sectors of the crystal. The refractive index at five different wavelengths in the range of 407–1551 nm and birefringence properties of Cd- and Mn-doped crystals were analyzed using the prism coupling method. The second harmonic generation capability of the material was studied using the Kurtz and Perry technique. The pyroelectric coefficients of these crystals were determined by measuring the pyroelectric current as a function of temperature. Piezoelectric studies were carried out on the (010) surface of the undoped and doped samples. The LSMH crystals grown from a solution containing Mn ions were found to have a satisfactory second harmonic generation capability and piezoelectric coefficient.

Laser–host ceramics are a new class of materials and have proved to be a good alternative to the single-crystals. They can be produced in large size with higher concentration of activator ions having more homogeneity which is difficult to achieve with the conventional single-crystal growth technology. Ytterbium (Yb)-doped yttrium aluminium garnet (YAG) is a very attractive laser–host material because of its broad emission band, low quantum defect, no excited state absorption or up-conversion loss and wide range of tunability. In the present work, 10 atm% Yb-doped YAG transparent ceramic was fabricated using nano-powder technology and vacuum sintering. Single-phase nano-powders of Yb:YAG were synthesized by a co-precipitation method and thereafter sintered under vacuum at $$1750^{\circ }\hbox {C}$$ for 5 h. The as-sintered ceramic samples are of dark greenish colour which is attributed to the reduction of $$\hbox {Yb}^{3+}$$ to $$\hbox {Yb}^{2+}$$ during vacuum sintering. However, after annealing in air at $$1350^{\circ }\hbox {C}$$ for 8 h they retain their natural colour attributed to the transformations from $$\hbox {Yb}^{2+}$$ to $$\hbox {Yb}^{3+}$$. The transmission spectra of the as-sintered polished ceramics show the presence of broad absorption bands near 250, 380, 480 and 630 nm due to the electronic transitions in the $$\hbox {Yb}^{2+}$$ ion. These bands disappear after annealing in air. The well-established bands due to transitions in $$\hbox {Yb}^{3+}$$ were observed between 900 and 1000 nm.

Undoped and Nd (0.2, 0.6, 0.8, 1.0, 1.2 and 1.6 at%)-doped GdVO4 single crystals have been grown by optical floating zone technique. XRD analysis reveals small lattice expansion especially along c axis on Nd doping. It has been observed that the extra-ordinary refractive index (RI) of undoped GdVO4 crystals is higher than the doped GdVO4 single crystals up to 1.0 at% Nd doping, beyond which it surpasses the value of the undoped crystal. This is due to the competing effect of lattice elongation and decrease in electron density on Nd doping. The increase in RI with Nd doping is attributed to macroscopic polarization effects. Moreover, the extra-ordinary refractive index (ne) only increases on increasing Nd concentration, whereas ordinary refractive index (no) remains unaffected within the measurement limits. The temperature-dependent RI measurements depicted a positive thermo-optic coefficient (TOC) for RI and birefringence, which is ~ 10−5/°C and is independent of doping concentration. TOC for ne is higher than no, which has been explained on the basis of anisotropic thermal expansion. An important set of relations between TOC and wavelength (532–1551 nm) has been established which is useful for estimating TOC in the temperature range of 30–150 °C.

Single crystals of Cr-co-doped 0.7 at.% Nd:YVO4 were grown using the optical floating zone method with varied Cr doping concentrations (0.7, 1.0, 1.4 and 2.0 at.%) in different oxygen partial pressures. The lattice parameters are unaffected by Cr doping. Further, the effect of the doping concentration and the growth atmosphere on the optical absorption, particularly for the 2A1→2B2 transition, which is due to the pentavalent state of Cr ion, has been investigated under two orthogonally polarized lights (i.e., E ⊥ [001]) and E ǁ [001]). This transition is important as it results in saturable absorption that is used for self-Q-switching of laser output. The observation suggests that the concentration of the desired pentavalent Cr increases to 1.4 and 2.0 at.% Cr as the oxygen partial pressure in the growth ambience increases, whereas for 0.7 and 1.0 at.% of Cr, the increase in the oxygen partial pressure results in an adverse effect. This finding suggests that on the basis of the concentration of Cr5+ required in Nd:YVO4 to attain the desired level of saturable absorption, the growth ambience should be chosen judiciously so that it is in line with the result presented here.

The optimization of dopant concentration in upconverting nanophosphor is a real problem because of distinct limits defined by surface quenching, energy transfer and cross relaxation phenomenon. In this work, LaF3 based nanophosphors with different doping concentration of Yb3+ and Tb3+ ions were prepared by coprecipitation route. Particles are formed in spherical shape with narrow size distribution i.e. in ∼50–80 nm range. The volume of LaF3 unit cell shrinks with the doping of Tb3+ and Yb3+, whereas no variation in its phase were observed. The nanophosphors exhibit characteristics of dual mode spectral emitter. Thus, irrespective of excitation source (i.e. either UV or NIR), the intense green emission at 541 nm was observed. The material LaF3 with optimized molar doping concentration of 5%Tb3+ and 10%Yb3+ shows intense green emission on excitation with either UV or IR light. The time resolve luminescence emission were studied to explore the probability of involved energy transfer process between two dopant ions.

Nickel (Ni7+) Swift Heavy Ion (SHI) irradiation effects on the optical, topological, dielectric, piezo- electric and ferroelectric properties of 〈0 1 1〉 oriented ferroelectric Triglycine sulphate (TGS) single crystals have been investigated. Dielectric constant found to have increased more than 9 fold upon irradiation. A marginal shift in Tc (325–332 K) has been noted upon irradiation. A significant improvement in the piezoelectric coefficient has been observed for irradiated samples when compared to the 〈0 1 1〉 pristine TGS. Ferroelectric studies reveal the decrease in coercive field due to the irradiation with Ni7+ ions. The results obtained from all studies have been discussed in detail.

Nd (0.8 at.%) co-doped Yb (0.8 and 3.0 at.%):YVO4 single crystals were grown by optical floating zone technique for the first time to the best of our knowledge. The absorption spectra revealed strong absorption for π-polarization (E||c) than the σ-polarization (E⊥c) for both the Yb concentrations due to anisotropy of the crystal. The estimated effective Judd-Ofelt parameters are 11.8675 × 10−20, 5.1577 × 10−20 and 7.3755 × 10−20 cm−2. Spectroscopic quality factor of Nd co-doped Yb:YVO4 are 0.70. which is lower than that of Nd (1.0 at.%) doped YVO4 (0.97), which indicates the energy transfer from Nd3+ ion to Yb3+ ion inside the host matrix. The estimated emission cross-section of 4F3/2 → 4I11/2 Nd transition with an excitation at 808 nm for both the concentrations of Yb is ∼4.0 × 10−19 cm2 which is almost same as estimated by Bhaumik et al. (2014) [21] for Nd:YVO4. Hence emission cross-section of 4F3/2 → 4I11/2 Nd transition is not effected by Yb co-doping. Also the PL intensity of Yb at 1010 nm enhances with Yb co-doping for same Nd (0.8 at.%) this is because the Nd3+ ion effectively excites the Yb3+ ion in upper state. Therefore Nd3+ ion acts as excellent sensitizer for Yb:YVO4 laser gain medium and make efficient pumping in the gain medium.

MgFe2O4 (MFO) and (Ba0·85Ca0.15) (Zr0·1Ti0.9)O3 (BCZT) was prepared by solid state route and are found to be ferromagnetic and ferroelectric at room temperature respectively. MFO/BCZT composite (50:50 M concentration of MFO and BCZT) was also prepared by solid state route. Multiferroic properties of MFO/BCZT ceramic composite were investigated. Scanning electron micrograph confirms the distribution of small grains of MFO around large grain of BCZT for proper surface interaction. MFO/BCZT composite exhibits saturated magnetization of 12 emu/gm, which reduce to 10 emu/gm on electrical poling at 2.5 kV/cm indicating magneto-electric coupling between MFO and BCZT through interface interaction. The composite also exhibits proper ferroelectric polarization, which is confirmed from I–V characteristic plot (occurrence of double minima as that of proper ferroelectric). The transverse magnetoelectric coupling coefficient (αV31) for this composite is found to be 7.97 mVcm−1Oe−1 at 10 kHz. MFO/BCZT ceramic composite exhibit multiferroic and magnetoelectric coupling properties for 50:50 M concentration at room temperature may be suitable for device applications.

Good quality, large size (010) polar face oriented ferroelectric single crystals of l -alanine doped triglycine sulphate (LA-TGS) were grown by unidirectional solution growth technique in two temperature regimes on either side of its Curie temperature (Tc). The growth conditions were optimized to obtain LA-TGS crystals of length = 40 mm, diameter = 30 mm below Curie temperature (Tc), and length = 50 mm, diameter = 15 mm above Curie temperature, with growth rates of 1.3 and 3.0 mm/day, respectively. Powder XRD was performed for phase confirmation and DTA for phase transition temperature determination, and compared with data of undoped TGS crystal. Crystal grown below Tc has almost same dislocations density, two times higher piezoelectric d33 coefficient, and three times lower dielectric permittivity as compared to the crystal grown above Tc, showing its better device potential. The UV-Vis-NIR transmittance of the two crystals was ≥80 %, showing their good optical quality.

Single crystals of Samarium orthoferrite (SmFeO 3 ) have been grown by the optical floating zone technique. The growth parameters to yield good quality crystals are 5 mm/h for pulling and 30–40 rpm for rotation. The mechanical behavior of the grown crystal has been investigated. Rosette pattern has been observed around the indentation and the microhardness has been found to decreases non-linearly with the applied load. For load higher than 1.96 N there is a transition from palmqvist to median crack due to plastic deformation of the crystal. The hardness parameters like fracture toughness, brittleness index, and yield strength have also been calculated for palmqvist and median cracks occurring on the crystal surface. The magnetic investigations revealed that a magnetic transition in the range of 300–180 K. Above 180 K, the magnetization decreases as Sm and Fe sublattices have opposite spins. At high temperature, two anomalies are observed, one due to near spin reorientation (T SR = 480 K) and the other is AFM to paramagnetic transitions (T N = 670 K). The M–H curves exhibit a shape change with temperature due to the emergence and enlargement of multi-domain state of the SmFeO 3 crystals. Bloch parameter (3.28 × 10 −5 K −3/2 ) has also been evaluated.