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Background: The combination of an anti-CD38 monoclonal antibody, Dara, to the main induction protocols (VRd, VTd,VCd) significantly improved the response rate of TE NDMM before transplantation. However, there is a concern regardingthe possible interference in the SC collection and bone marrow engraftment, since SC, to some degree, express CD38on their surface. In the MAX Dara study, Dara-CTd protocol was used sequentially close to the pre- and post-autologousstem cell transplantation-(ASCT) (D-30 and D + 30), in order to take advantage of the molecule's action as an in vivopurge. Aims: In this analysis, we examine the impact of the number of Dara doses administered pre-mobilization on CD34 cellcount, SC apheresis yield, and post-ASCT engraftment. Methods: This is a phase II, open-label single-center clinical trial. The original protocol was Dara-CTd for up to four 28-day induction cycles and Dara-Td for up to four 28 days consolidation cycles. C-1500 mg oral (PO) per cycle, duringcycles 1 to 4, T at 100-200 mg PO on days 1 to 28, during cycles 1-8, (d) at 160 mg PO per cycle, during cycles 1 - 8 andDara at 16 mg/kg/dose intravenous (IV) on days 1,8,15 and 22 during cycles 1 - 2 and every other week in cycles 3 – 8. Because of the Covid pandemic we had to adapted the protocol and moving 5-6 consolidation cycles to be used asinduction, increasing the total dose of Dara from 12 to 16 and the number of cycles from 4 to 6 before ASCT. Granulocytecolony-stimulating factor (G-CSF) was administered alone for SC mobilization and plerixafor added based on day 4 preharvestperipheral blood CD34 counts. The target of SC collection was to enable the performance of one ASCT (>2,5 x 106/kg). PMN and platelet engraftment post-ASCT was defined as the first day with sustained PMN count >1000 x 106/L andindependence from platelet transfusion in the preceding 7 days with a count >20 x 109/L, respectively Results: From a total of 21 pts that were included, 19 pts completed mobilization. 12 pts received 12and 7 pts received 16 induction Dara doses, respectively. The median number (range) of daysbetween the last dose of Dara infusion and SC harvest was 23 (16-63) days. A total of five (26%) ptsreceived plerixafor during mobilization. More pts from Dara 16 doses needed plerixafor comparingwith Dara 12 doses (42% vs 16%), but without difference between the groups. Pts underwent amedian (range) of 1 (1-2) days of apheresis. The median number of CD34+ cells collected in the totalgroup was 3.94×106/kg, and no difference was found between Dara 12 vs 16 doses (3.61×106/kg vs4.01x106/kg), p = 0.27. There was no difference in the number of SC collected considering theresponse rate after induction > or < VGPR, and the last day of Dara use > or < 30 days, before SCharvesting. Hematopoietic reconstitution rates were similar for Dara 12 vs 16 doses, a median(range) of 11.0 (9-13) vs 11.0 (11-14) days was required to achieve sustained ANC > 1000 cells/mm3, and a median (range) of 12.0 (9-14) vs 11.0 (8-16) days was required to achieve sustained platelets> 20,000 cells/mm3 without transfusion, respectively. Summary/Conclusion: SC mobilization was feasible with Dara-CTd induction. Despite the more doses of Dara usebefore mobilization increases the need of plerixafor use, the SC number difference was not significant comparing Dara 12vs 16 doses (p = 0.3). The infusion of Dara close to harvest did not interfere with SC collection. Adding DARA to CTdallowed successful transplantation in pts with TE NDMM.

Background Newly drugs access for MM treatment still a challenge in some countries. One of the most availableinductions for TE NDMM patients (pts) worldwide is cyclophosphamide (C), thalidomide (T) and dexamethasone (d)-(CTd). Dara the first anti- CD38, had been combined with VCd, VTd and VRd and markedly increased the depth andduration of the response. We hypothesized that the combination of Dara and CTd could be safe and allow deeper activityas an alternative protocol. Aims The primary endpoint was to evaluate the VGPR after two consolidation cycles post-autologousstem cell transplantation (ASCT). Secondary endpoints were the overall response rate during alltreatment phases and minimal residual disease (MRD), based on the International Myeloma WorkingGroup (IMWG) criteria that includes the next-generation flow (NGF) by the EuroFlow®and PET-CTand the safety profile. Methods This is a phase II, open-label single-center clinical trial. The main inclusion criteria were: TENDMM, creatinine clearance > 30 mL/min, normal cardiac, renal and liver function and the EasterCooperative Oncology Group (ECOG) performance status = 0 - 2. The protocol was Dara-CTd for upto four 28-day induction cycles: C-500 mg oral (PO) on days 1,8 and 15, T at 100-200 mg PO on days1 to 28, (d) at 40 mg PO on days 1,8,15 and 22 and Dara at 16 mg/kg/dose intravenous (IV) on days1,8,15 and 22 during cycles 1 - 2 and every other week in cycles 3 – 4, followed by ASCT. All ptsreceived up to four 28-day consolidation cycles that was started at D+30 after ASCT: Dara at 16 mg/kg and (d) at 40 mg every other week, associated with T at 100 mg PO on days 1 - 28. Dara at 16 mg/kg was used monthly as maintenance until progression or limiting toxicity. G-CSF was used forstem cell (SC) mobilization and plerixafor had been allowed whenever the pts need. All pts receivedantiviral, anti-pneumocystis and anti-thrombotic prophylaxis. Results The first pts was enrolled in November 2018. A total of 21 pts were included, the median age being 56 (range 37– 67 years), 19 (90%) were non-white, 3 (14%) had an R-ISS = 1, 12 (57%) had an R-ISS = 2 and 3 (14%), an R-ISS = 3. Five (24%) pts had high-risk chromosomal abnormalities [del17p, t(4;14) or t(14;16)]. To date, all pts have completedinduction, 19 have received transplant and 17 have completed D+90 post-transplant assessment. No SC mobilizationfailure was observed, and five (26%) pts needed plerixafor use. In an intention to treatment analysis, after the end ofinduction (cycle 4), 19 (90%) of the pts obtained > PR and 8 (38%) obtained >VGPR, including three MRD negativity byNGF. 17 pts have completed two consolidation cycles after transplant and 94% obtained > VGPR as best response, 12(70%) obtained MRD negativity by NGF and nine (53%) had negative PET-CT. Seven (41%) pts had both flow and PETCTnegativity. Three pts died from infection, one before transplant because of Covid infection, on post-transplant, considered not related to the investigational agent, and another after consolidation, related to the investigational agent. The most common nonhematological adverse events (AEs) grades 3 and 4 before ASCT were neuropathy (n = 6), infusion reaction (n = 7), infection (n = 2), hypertension (n = 1) and rash (n = 1). Summary/Conclusion This is the first study that combined Dara with CTd as induction for TE NDMM pts. This presentdata has shown that the association of Dara-CTd achieved the primary end point once > 90% of the pts achieved VGPRafter two consolidations cycles, and safety profile was acceptable. Clinical trial information NCT03792620.

Background: Newly drugs access for MM treatment still a challenge in some countries. One of the most available inductions for TE NDMM patients (pts) worldwide is cyclophosphamide (C), thalidomide (T) and dexamethasone (d)-(CTd). Dara the first anti- CD38, had been combined with VCd, VTd and VRd and markedly increased the depth and duration of the response. We hypothesized that Dara and CTd combination could be safe and allow deeper activity as an alternative protocol. Aims: The aims of this analysis were to evaluate Progression Free Survival (PFS) of Dara-CTd treatment and minimal residual disease (MRD) after one year of Dara maintenance. Primary endpoint of the study was to evaluate the VGPR after two consolidation cycles post-autologous stem cell transplantation (ASCT). Methods: This is a phase II, open-label single-center clinical trial. The main inclusion criteria were: TE NDMM, creatinine clearance > 30 ml/min, normal cardiac, renal and liver function and the Easter Cooperative Oncology Group (ECOG) performance status = 0 - 2. The protocol was Dara-CTd for up to four 28-day induction cycles: C-500mg oral (PO) on days 1,8 and 15, T at 100-200mg PO on days 1 to 28, (d) at 40mg PO on days 1,8,15 and 22 and Dara at 16mg/Kg/dose intravenous (IV) on days 1,8,15 and 22 during cycles 1 - 2 and every other week in cycles 3 - 4, followed by ASCT. All pts received up to four 28-day consolidation cycles that was started at D+30 after ASCT: Dara at 16mg/Kg and (d) at 40mg every other week, associated with T at 100mg PO on days 1 - 28. Dara at 16mg/Kg was used monthly as maintenance until progression or limiting toxicity. G-CSF was used for stem cell (SC) mobilization and plerixafor had been allowed whenever the pts need. The MRD was evaluated by next-generation flow (NGF) based and PET-CT was performed when the patient obtained NGF negativity or finished consolidation. PFS outcome was estimated using Kaplan-Meier method. All pts received antiviral, anti-pneumocystis and anti-thrombotic prophylaxis. Data cut-off was June 15, 2021. Results: The first pts was enrolled in November 2018. A total of 24 pts were included, the median age being 60 (range 37- 67 years), 23 (92%) were non-white, 5 (21%) had an R-ISS = 1, 12 (54%) had an R-ISS = 2 and 4 (16%), an R-ISS = 3. Six (25%) pts had high-risk chromosomal abnormalities [del17p, t(4;14) or t(14;16)]. To date, all pts have completed induction, 20 have received transplant and 17 have completed D+90 post-transplant assessment. No SC mobilization failure was observed, and six (30%) pts needed plerixafor use. By ITT analysis after a median follow up of 20 months the PFS at 12 and 18 months was 86%. No PFS difference was observed between different subgroups. Regarding response rates, after the end of induction (cycle 4), 19 (90%) of the pts obtained > PR and 8 (38%) obtained >VGPR, including three MRD negativity by NGF. 17 pts have completed two consolidation cycles after transplant and 94% obtained > VGPR as best response, 13 (76%) obtained MRD negativity by NGF and 10 (58%) had negative PET-CT. Seven (41%) pts had both flow and PET-CT negativity. Six pts completed one year of maintenance and five of them (83%) still MRD negativity by NGF. Four pts died from infection, two of them related with covid infection (one before transplant and one during maintenance). Another case post-transplant, considered not related to the investigational agent and one after consolidation, related to the investigational agent. Two pts have discontinued treatment due to progression - 1 before ASCT e 1 during maintenance. The most common adverse events (AEs) grades 3 and 4 were neutropenia (n = 12), infusion reaction (n = 7), neuropathy (n = 6), lymphopenia (n = 4), infection (n = 3), hypertension (n = 1) and rash (n = 1). Summary/Conclusion: The Daratumumab - CTd protocol is an active regimen capable of producing deep and sustainable responses and improve the PFS of NDMM TE pts with a favorable safety profile. Clinical trial information: NCT03792620. Disclosures De Queiroz Crusoe: Janssen: Research Funding. Hungria: Sanofi: Honoraria, Other: Support for attending meetings/travel ; Takeda: Honoraria; Abbvie: Honoraria; Amgen, BMS, Celgene, Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Support for attending meetings/travel .

Introduction- Next generation flow (NGF) is one of the approaches for testing multiple myeloma (MM) minimal residual disease (MRD) over conventional response assessments. Actually, bone marrow (BM) is the preference site of evaluation because of its sensitivity. Because of its invasively technic, other possible sites for MRD evaluation outside the BM have been studied. In the present study we analyzed the MRD between the BM and the hematopoietic stem cell collected product (HSC product), once the concentration of plasma cell in the HSC product could be higher than peripheric blood sample. Aims- To compare MRD quantification of plasma cell between BM and HSC product after induction from Newly Diagnosed MM(NDMM) Transplant Eligible (TE) patients (pts) exposed to daratumumab, cyclophosphamide, thalidomide and dexamethasone (Dara-CTD) protocol. Methods- The SC product and BM samples were collected after four 28 days cycles of induction therapy from pts treated with Dara-CTd protocol described before by (Crusoe E. et al. Blood 2020; 136 (supplement 1): 17-18). MRD was evaluated by next-generation flow (NGF) based in the EuroFlow® protocol. EuroFlow standards was used to identify clonality and aberrant PC immune phenotype, consisting by EuroFlow 8-color 2-tube method (MM MRD kit, Cytognos, Salamanca), with the acquisition of 5 million events each tube and then merged into a single analysis tube on approximately 10 million events. Plasma cells were identified by CD38 multiepitope and CD138. Other markers were used to detect abnormal phenotypes. For comparison of MRD results, Bland-Altman plot comparing BM-MRD and HSC product-MRD was performed. Results- The first pts was enrolled in November 2018. A total of 24 pts were included, the median age was 60 (range 37- 67 years), 23 (92%) were non-white, 5 (21%) had an R-ISS = 1, 12 (54%) had an R-ISS = 2 and 4 (16%), an R-ISS = 3. Six (25%) pts had high-risk chromosomal abnormalities [del17p, t(4;14) or t(14;16)]. To date, all pts have completed induction and 20 have received transplant. Regarding response rates, after the end of induction (cycle 4), 19 (90%) of the pts obtained > PR and 8 (38%) obtained >VGPR, including three MRD negativity by NGF. 19 pts were analyzed for MRD. Negative MRD in sensitivity =10 -5 and =10 -4 evaluated in bone marrow was 4/19(21%), 4/19(21%), 11/19(58%) respectively. Negative MRD in sensitivity =10 -5 and =10 -4 evaluated in the HSC product was 13/19(68%), 3/19(16%), 3/19(16%) respectively. Median bone marrow sensitivity 10 -4 lower quartile 10 -5 upper quartile 10 -3. Normal distribution of the differences between BM and SC product MRD was first assessed (Kolmogorov-Smirnov's p < 0.001, n = 19). Discussion-Conclusions- The use of HSC product could enhance the plasma cell concentration and may be an alternative and attractive method for MRD detection that diminished the invasiveness of repetitive bone marrow aspirations and tackling the heterogeneity distribution of MM cells. In this preliminary data the sample size did not allow to show a direct correlation between BM and HCS product. A larger sample would be needed to confirm the hypothesis. Figure 1 Figure 1. Disclosures Hungria: Amgen, BMS, Celgene, Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Support for attending meetings/travel ; Abbvie: Honoraria; Sanofi: Honoraria, Other: Support for attending meetings/travel ; Takeda: Honoraria. De Queiroz Crusoe: Janssen: Research Funding.

In the MAX Dara study, Dara-CTd was used sequentially close to the pre- and post-ASCT (D-30 and D + 30), in order to take advantage of the Dara as an in vivo purge. However, dara could interfer in the SC collection and bone marrow engraftment. In this analysis, we examine the impact of the number of Dara doses administered pre-mobilization on CD34 cell count, SC apheresis yield, and post-ASCT engraftment. This is a phase II, open-label single-center clinical trial. The original protocol was Dara-CTd for up to four 28- day induction cycles and Dara-Td for up to four 28 days consolidation cycles. C-1500mg PO per cycle, during cycles 1 to 4, T at 100-200mg PO on days 1 to 28, during cycles 1-8, (d) at 160mg PO per cycle, during cycles 1 - 8 and Dara at 16mg/Kg/dose IV QW during cycles 1 - 2 and QOW in cycles 3 – 8. Because of the COVID pandemic we had to adapted the protocol and moving 5-6 consolidation cycles to be used as induction, increasing the total dose of Dara from 12 to 16 and the number of cycles from 4 to 6 before ASCT. G-CSF was administered alone for SC mobilization and plerixafor added based on day 4 preharvest PB CD34 counts. The target of SC collection was (>2,5×106/kg). PMN and platelet engraftment post-ASCT was defined as the first day with sustained PMN count >1000×106/L and independence from platelet transfusion in the preceding 7 days with a count ≥20×109/L, respectively. From a total of 21 included pts, 19 pts completed mobilization. 12 pts received 12 and 7 pts received 16 induction Dara doses, respectively. The median number (range) of days between the last dose of Dara infusion and SC harvest was 23 (16-63) days. A total of five (26%) pts received plerixafor during mobilization. More pts from Dara 16 doses needed plerixafor comparing with Dara 12 doses (42% vs 16%), but without statistic difference. Pts underwent a median (range) of 1 (1-2) days of apheresis. The median number of CD34+ cells collected in the total group was 3.94×106/kg, and no difference was found between Dara 12 vs 16 doses (3.61×106/kg vs 4.01×106/kg), p=0.27. There was no difference in the number of SC collected considering the response rate after induction > or or 1000 cells/mm3, and a median (range) of 12.0 (9-14) vs 11.0 (8-16) days was required to achieve sustained platelets >20,000 cells/mm3 without transfusion, respectively. In summary, SC mobilization was feasible with Dara-CTd induction. Despite the more doses of Dara use before mobilization increases the need of plerixafor use, the SC number difference was not significant comparing Dara 12 vs 16 doses (p=0.3). The infusion of Dara close to harvest didn’t interfere with SC collection. Adding DARA to CTd allowed successful transplantation in pts with TENDMM.

Inelastic light scattering is used to study lattice dynamics of strontium titanate (STO) ceramics with several heterovalent dopants(La 3+ ,Gd ,Y ), which substitute Sr 2+ ions. An extraordinary shift of the antiferrodistortive transition temperature (T a ) is ascertainedwhen just a small percentage of any of the dopants is used. T a is dependent on the tolerance factor (t). In this work, it is clearly shownthat, regardless of the dopant used, a common linear dependence of T a vs. t is obtained if strontium vacancies are taken into account. Avacancy size of 1.547 A˚ was estimated, which is 7% larger than the Sr 2+ radius. The vacancy size obtained can directly explain theincrease in lattice parameter with increasing Bi 3+ content in Bi-doped STO, as opposed to the dopants referred to above. Furthermore,the introduction of La 3+ ,Gd or Y ions at the Sr site causes a considerable stiffening of the transverse optic TO 1 mode at low tem-peratures, thereby decreasing the phonon contribution to the dielectric permittivity. Thus, no traces of a ferroelectric phase are found forany of the dopants used in this work. 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

This work reports an experimental investigation of the ferroelectric character of magnetic phases of the orthorhombic Eu1−xY xMnO3 system at low temperatures. The temperature dependence of the polarization curves clearly reveals the existence of a re-entrant improper ferroelectric phase for x = 0.2 , 0.3 and 0.5. A ferroelectric phase is also stable for x = 0.4 , and we have no experimental evidence for its vanishing down to 7 K. From these and early results obtained using other experimental techniques, the corresponding ( x , T ) phase diagram was traced, yielding significant differences with regard to the ones previously reported.

This work is addressed to study the crystal structure and morphology, as well as the thermodynamic, dielectric and magnetic properties of Eu0.8Y0.2MnO3 ceramics, synthesized by urea sol-gel combustion method. The experimental results were systematically compared with data available for the corresponding single crystals. Though the effect of the anisotropy on both dielectric and magnetic properties is missing, they enabled us to investigate the main physical mechanisms associated with their magnetoelectric properties, in particular the one which drives the ferroelectric phase. The phase sequence and critical temperatures are in good agreement with the corresponding values reported for single crystals. Similarly, structural results evidence strong distortions of the crystal lattice, enhancing the ferromagnetic interactions over the antiferomagnetic ones. A significant contribution of the magnetic fluctuations above TN was also evidenced from the magnetization studies.

In an attempt to gain a better understanding of the lattice dynamics in lanthanum doped SrTiO3 (STO) ceramics, with general formulae LaxSr(1-1.5x)TiO3, we have carried out a detailed Raman study of the x=0.0133 ceramic in the temperatures ranging from 10K to room temperature. Our results show that lanthanum substitution gives rise to new features in the Raman spectra. The Rayleigh band and the extra Raman-forbidden infrared active modes observed provide evidence for the existence of disorder in the system, apparently associated with grain structure, and lattice defects. Moreover, the absence of a TO1 polar soft mode supports the non-existence of a ferroelectric phase at low temperatures. The shift of the para-antiferrodistorsive transition temperature towards higher temperatures clearly evidences that the replacement of Strontium by Lanthanum occurs at the lattice A-site.

We have attempted to understand the low temperature microscopic structure and dipolar ordering of the (BP)x(BA)1 −x mixed system in a previous work, by performing detailed pyroelectric, dielectric and polarization reversal measurements, complemented with Raman and infrared spectroscopic investigations. Whenever the same experimental techniques are used, our experimental results agree extremely well with those reported in the literature. However, our use of slightly different methods disclosed new aspects of the phase sequence, which allowed us to trace an alternative phase diagram for the (BP)x(BA)1−x mixed system. The present paper is aimed at emphasising the most relevant of these previous results. Particular attention will be paid to the role of ferro-antiferroelectric competitions in the mixed system (BP)x(BA)1 −x.

Raman scattering was investigated in high-quality SrBi2Ta2O9 (SBT) single crystals prepared by the self-flux solution method. The Raman spectra in the range 6–1800 cm−1 were monitored as a function of temperature both below and above the ferroelastic–ferroelectric phase transition at about 600 K. The behaviour of the soft ferroelectric mode and of its damping coefficient near the phase transition indicates a strong coupling with an acoustical phonon. The results provide clear evidence for a crossing over from a displacive to an order–disorder component and they are discussed in terms of a complex sequence of the phase transitions in SBT.

Lattice dynamics and polar properties in lanthanum doped SrTiO3 (STO) ceramics, with general formulae Sr(1− 1.5 x)La x TiO 3 were studied in the temperature range between 10 K and room temperature. Despite the similarities of the low frequency Raman spectra, for differently (x = 0.0533, 0.080 and 0.133) La-doped ceramics, and the spectra of the undoped ceramics, the TO 1 polar soft mode could not be detected in those systems, which confirms the non-existence of a ferroelectric phase at low temperatures. Raman spectra analysis provides evidence for drastic effects determined by La 3+ impurity in the critical temperature shift of the para-antiferrodistortive phase transition of STO, accompanied with a continuing change of the lattice dynamics by increasing lanthanum concentration. The absence of a pyroelectric current confirms the non-existence of a polar character in the low temperature range. The existence of semiconduting like behaviour at high temperatures was disclosed.

In this work we present a detailed study of the temperature dependence (35 K – 290 K) of the Raman spectra in a single crystal of betaine phosphite. A softening of a relaxational mode is observed above and below the para-ferroelectric phase transition at Tc2∼ 213 K, which appears to have its primary origin in the different internal dynamic deformations and reorientations of molecular units. Our results suggest the existence of a certain degree of local disorder between 110 K and 170 K.

Betaine calcium perchlorate monohydrate (here designate by BCPM) is a new compound of the aminoacid betaine with a triclinic symmetry and with the space group P , at room temperature. In this work we present a detailed study of dielectric properties and of Raman scattering spectra of BCPM, which disclose interesting structural changes in the temperature range 20 K–300 K.

The study of the Raman intensity of the ‘breathing’ mode of the benzene rings as a function of the temperature in smectic phases revealed strong anomalies of the intensities IZZ and IYY in SmCFI2* and SmCFI1* phases, as well as an important shift of the principal optical direction with respect to other smectic phases. The analysis of these results provided evidence for significant structural changes at the SmC*–SmCFI* and SmCFI*–SmCA* phase transitions, because the molecules can no longer be treated as cylindrical rods. No anomalies in the tilt angle were found. Experimental results suggest a relationship between the deviation of the optical axis and the particular structure of the SmCFI* phases. The deviation of IZZ maxima as a function of the rotation angle Ψ and the behaviour evident under an electric field in SmCFI* and SmCA* phases clearly excludes the coexistence of SmCA* and SmC* local domains in SmCFI* phases.

X-ray diffraction (XRD) and Raman scattering in sol–gel derived Pb1−xCaxTiO3 (PCT) thin films are studied as a function of Ca content x. It is found that Ca2+ addition to PbTiO3 films results in a gradual decrease of tetragonality of the perovskite lattice accompanied with a considerable modification of the Raman spectra. A significant difference in Raman spectra of PCT films and available reference data for single crystals (x=0) is explained in terms of the large internal stress, small grain size, and structural disorder produced by Ca2+ substitution. It is found that the shift of the frequency of ferroelectric soft mode correlates well with the variation of tetragonality for x≤xc=0.4. The concentration dependence of the shift is strongly non-linear being qualitatively different from that observed earlier in other A-site doped lead titanate-based systems. According to XRD data, the averaged crystal structure for xc≈0.4 appears as pseudo-cubic, while Raman scattering revealed short-range order tetragonal distortion. The structural characteristics of PCT films are linked to their electromechanical properties measured earlier by interferometric technique.

From a phenomenological point of view, the dielectric dispersion function of a medium can be defined by the location of its zeros and poles in the complex-frequency plane. This general approach led to the use of a factorized form of the dielectric function to fit the experimental infrared reststraheln data. Recently, such an approach has been generalized to the description of relaxation. At low frequency ranges, the factorized form for relaxation may be expressed as a product of Debye relaxors. This product form corresponds to the factorization of the conventional sum model and provides a way to describe the contribution of the different Debye relaxing units in a poly-dispersive system. It also allows us to estimate the importance of the interaction between the different relaxing units. The present work summarizes the fundamentals of the product model for relaxation and describes its application to the analysis of the dispersion observed in the vicinity of the paraelectric to antiferroelectric phase transition in the mixed crystal (betaine phosphate) 0.75 (betainearsenate) 0.25 and at the structural phase transition of betaine potassium iodide dihydrate.

Betaine cadmium chloride monohydrate undergoes a phase transition at 241 K. This transition was disclosed by using thermal differential analysis and Raman spectroscopy. This phase transition is clearly related to a structural change where the water molecules lose their degrees of freedom, becoming more tightly bonded, on cooling.

The mixed system of betaine arsenate and betaine phosphate (BP)x(BA)1−x displays, at low temperatures, dielectric anomalies that have been tentatively associated to re-entrant glass phases. In this work, we report results obtained for the composition x = 0.52. The temperature dependence of the complex dielectric constant, polarization hysteresis loops and pyroelectric currents reported prove that an effective ergodicity breaking occurs in the antiferroelectric phase and show that this phase is destabilized at low temperatures. There is also evidence for a high internal bias field, in the whole temperature range studied. Infrared and Raman spectroscopy indicate that the various dielectric anomalies observed reflect structural transformations.

Betaine arsenate (BA) and betaine phosphate (BP) are addition compounds of the amino acid betaine [(CH3)3N+CH2COO−] and arsenic and phosphoric acids, respectively. The mixed system (BP)x(BA)1 − x displays, at low temperatures, dielectric anomalies that have been interpreted as due to additional transitions to re-entrant glass phases originated by frustrated FE and AF interactions. In this work, Raman and infrared spectroscopic data are analysed and compared with results of complex dielectric constant, pyroelectric measurements performed during thermal cycles under different bias electric fields and low frequency polarization hysteresis loops. The results obtained for the x = 0.75 composition do not give any evidence for the stabilisation of a re-entrant glass phase or a non-ergodic regime, and a long-range order seems to prevail in the whole temperature range studied. The inclusion of BA is however capable of destabilising the AF order, giving rise to a slightly polar ferroelectric phase at low temperatur...

Raman spectra and pyroelectric studies in bismuth doped SrTiO3 ceramics, with general formulae Sr(1 − 1.5x)BixTiO3, were undertaken. For x = 0.0053, the low frequency Raman spectra exhibit striking similarities with the spectra of the undoped ceramics also revealing the existence of a polar soft-mode TO1, that obeys the classical Cochran softening law. The sample with x = 0.133 presents a very different dynamics, and its Raman spectra give evidence for the inexistence of an anti-ferrodistorsive phase transition, that occurs in the undoped ceramics at 104 K. Pyroelectric measurements disclose the existence of small electrical dipoles probably due to polar grain boundaries, off-centre positions of Bi3+ and Ti4+ ions, and Sr vacancies, that strongly influence the behaviour of these systems with temperature variation. There is a strong evidence for the existence of a relaxor state in the x = 0.133 ceramic at low temperatures.

Dielectric measurements and Raman spectroscopy have shown for betaine rubidium iodide dihydrate, with formula [(CH3)3N+CH2COO-]2RbI·2H2O, BRbI for short, the existence of two phase transitions in this compound, PT1 (at Tc1 = 190 K) and PT2 (at Tc2 = 90 K). The former phase transition is related to the loss of translational and librational degrees of freedom of water molecules and this, as shown by dielectric data, triggers a relaxation process leading to a complete `freezing in' of protons within the unit cell, and therefore, producing a proton-glass state.

We report a detailed experimental study of infrared reactivity and Raman spectroscopies in strongly deuterated betaine arsenate: BA 0.08 DBA 0.92 . The temperature dependence of the frequency of the hydrogen bonds stretching modes shows a different critical behaviour for the different types of hydrogen bonds. At 163 K , there is evidence for the proton ordering in the shorter hydrogen bond. A progressive softening of the dynamical central peak revelead some aspects of an order-disorder mechanism.

In this work we study the structure of the fourfold phase in a 2% brominated BCCD sample, above and below the so-called "strange anomaly" at T s , 93 K, in order to confirm the structural modification predicted by Neubert et al . on the basis of the Double Ising Spin model. The "internal transition" predicted by this model would correspond to a first order, symmetry conserving phase transition, that preserves the wavenumber of the commensurate phase and is characterized by a discontinuous increase of the symmetrized components of the structural modulation. The experimental results reported herein do not corroborate the quantitative predictions of the model.

Betaine potassium bromide dihydrate: (CH 3 ) 3 N + CH 2 COO m ·KBr·2H 2 O, for short BKBr, is a compound of the aminoacid betaine with an orthorhombic symmetry and the space group Pbcm at room temperature. The study of the dielectric properties of this compound, in the temperature range 20-300K, provides a clear evidence for the existence of a structural phase transition occurring around 160K. This phase transition is related to the freezing of water molecules degrees of freedom.

The SmC* phase of (R)-4-(1-methylheptyloxycarbonyl)phenyl 4'-(4-decyloxy-3-fluorobenzoyloxy)-benzoate, 10FHBBBM7*, shows an anomalous thermal hysteresis that is reflected in the values of the measured dielectric constant. When the cooling-heating cycle is repeated, a memory effect occurs. In this work, we present a detailed study and a tentative interpretation of this unusual effect.

We have performed a detailed experimental study of the electroclinic behaviour in the SmA* phase above a SmA*-SmC*A phase transition. The tilt angle and polarization were measured as a function of the applied a.c. electric field, and the dielectric constant was obtained under different values of the bias field (0≤E d.c.≤ 3 V μm-1). In the region of linear regime, the behaviour observed for this SmA*-SmC*A phase transition is very similar to the one previously described for SmA*-SmC* phase transitions. The experimental results obtained under high bias field are in good agreement with the predictions of the simple theoretical model considered.

We have performed a detailed dielectric study of three compounds presenting ferrielectric phases over large temperature intervals. The relaxation processes detected in the SmC*FI phases are highly polidispersive. We have repeatedly observed the surface layer mode described by Bourny et al. [1] and a weak ferrielectric mode, whose relaxation frequency is always higher on heating than on cooling runs. The temperature interval where SmC*FI phases occur is apparently independent of cooling/heating rates and of the history of the sample.

This work reports experimental results obtained from series of measurements of pyroelectric currents in samples of strontium calcium titanate (SCT) corresponding to contents of Ca of x = 0.002, x = 0.005 and x = 0.011. Sequences of zero field cooling (zfc), field heating (fh), field cooling (fc) and zero field heating (zfh) runs, under different applied electric fields, allowed the observation of the temperature and field dependence of the electric polarization under different initial conditions. The results show the existence of a weak non-ergodic regime in the compositions x = 0.005 and x = 0.011 and allow the tracing of the corresponding Almeida-Thouless line in the T-E diagram. For the three compositions investigated, a small zero field polarization is detected and interpreted as due to defect induced internal fields.

Polarized Raman spectra of tetragonally distorted (Ba 1-x Sr,)TiO 3 /MgO ferroelectric films were obtained in special scattering geometries using a micro-Raman set-up. The underdamped E(TO) soft mode was unambiguously observed in the films with x = 0.30 and 0.45. The low-temperature behaviour of the E(TO) soft mode for x = 0.45 was found substantially different from those observed in pure crystals and bulk solid solutions.

In this work we present a model that describes the influence of surface interactions on polarization hysteresis loops in thin liquid crystalline samples. Experimental results that illustrate this contribution are referred.

Polarized Raman spectra of betaine potassium iodide dihydrate ([(CH3 )3 N+ CH2 COO- ]2 KI 2H2 O) have been studied in the temperature range 40 - 290 K. The behaviour of betaine external modes and of water internal vibrations provides evidence for a first order phase transition of order-disorder type at 100 K. This phase transition is related to the freezing of the successive reorientations of water molecules. The temperature dependence of the halfwidth of the water stretching band centred at 3489 cm-1 (40 K) obeys an Arrhenius-type law corresponding to different activation energies below and above the critical temperature. The comparison of Raman and dielectric data allows us to identify two types of reorientation of water molecules.

Arrhenius plots of mean relaxation rates in dipolar glasses often show deviations from linear behavior at low temperatures. The upward curvature in these plots is usually attributed to quantum tunneling solely on the basis that a quantum tunneling rate should have a finite, nonzero value, at $T=0,$ without further quantitative analysis of experimental data. We find that experimental data of relaxation in several dipolar glasses fits quite well to detailed theoretical predictions for the crossover region between classical activation and quantum tunneling. The values of the parameters of the metastable potential barriers obtained from the fits raise some interesting questions about these often quoted deviations from Arrhenius behavior.

Integrated Raman intensity of the stretching mode of the benzene rings has been studied as a function of temperature in order to determine the peculiarities of the phase sequence in new chiral liquid crystals.

This work reports a study of the temperature and electric field dependence of the dielectric constant of strontium calcium titanate. The first part of the paper is focused on the analysis of a mean-field model for the polar clusters generated by the random impurities of calcium. It is shown that the dipolar moments within each cluster can be represented by an equivalent quantum two-level system. General expressions for the temperature and field dependence of the Edward-Anderson order parameter and of the electrical polarization are given. Analytical solutions are also obtained in the limit of high temperatures and in the limit of high tunnelling frequencies. The second part of the work reports experimental results on the temperature and electric field dependence of the dielectric constant of strontium calcium titanate (SCT: Sr1-xCaxTiO3), measured along the [100] pseudo-cubic direction, in samples with nominal Ca content of x = 0.002 and x = 0.003. The analysis of the data suggests that for these low Ca concentrations quantum fluctuations prevent the onset of either a ferroelectric or a glass phase.

Polar relaxation processes in Lanthanum doped SrTiO3 (STO) ceramics, with general formulae Sr(1−1.5x)LaxTiO3, were studied by undertaking field-induced thermally stimulated currents measurements below room temperature. The experimental results obtained for doped ceramic (x = 0.0133) were analysed by using dipolar and space-charge relaxation thermally stimulated depolarization currents (TSDC) models in order to determine the nature of the relaxation processes involved. Our results reveal the existence of different relaxation processes in the temperature range 60–300 K. Whereas at low temperature, a relaxation mechanism of a dipolar type was disclosed within the temperature interval centred around 100 K, a space-charge relaxation process could be identified in the temperature range 120–300 K. The temperature dependence of the relaxation parameters will be also discussed in detail.

Betaine potassium iodide dihydrate, , BKI for short, is a new compound of the aminoacid betaine with a triclinic symmetry and the space group at room temperature. The study of dielectric properties provided evidence for the existence of a structural phase transition occurring around 100 K. The spontaneous electric polarization is zero in both phases. A study of dielectric dispersion disclosed two relaxational modes with different relevance in the high and in the low temperature phases. The main features observed in BKI are consistently described by the Landau theory, by assuming a quadratic coupling between the primary order parameter and the electric polarization.

We have measured the polarized Raman spectra of betaine arsenate and deuterated betaine arsenate single crystals in the temperature range 12-300 K. On the basis of the comparative study of Raman spectra of protonated and deuterated compounds and by taking into account the relevant literature data, we proposed a mode assignment for . The isotopic effect in this system is discussed. The analysis of the internal modes of clearly shows the important role played by this unit in the phase sequence of . The strong coupling exhibited by the proton/deuteron modes with the internal modes of provides some evidence for the ordering of the hydrogen bonds at the phase transitions. In this analysis reveals the existence of two types of hydrogen bond related to the mechanisms underlying the phase transitions.

The temperature dependence of complete infrared reflection spectra of a betaine phosphite single crystal is reported for the polarizations parallel to a and b axes in the wavenumber range from 10 to . They are compared with previous data that were limited to the range . They are also compared with reflectivity spectra of betaine phosphate, betaine arsenate, deuterated betaine phosphite single crystals and betaine compressed powder. These comparisons allow a mode assignment. Spectra were fitted with the factorized form of the dielectric function. The role of phonons in the behaviour of the dielectric constant in the vicinity of the ferroelectric (FE)-paraelectric (PE) phase transition is discussed. The decrease of effective charges along the FE axis below the FE-PE phase transition is assigned to an increase of oxygen-hydrogen electronic orbital hybridization related to the change of average bond-length.

This work reports the study of the dielectric relaxation of betaine arsenate (BA) and of strongly deuterated betaine arsenate (DBA92) below room temperature for different values of d.c. electric fields, in the frequency range of 50 Hz-13 MHz. The main contributions for dielectric constant come from low-frequency relaxation modes. Some evidence for the existence of a new antiferroelectric phase in BA was found, stable in a short range of temperatures.

This work reports a study of FIR reflectivity in betaine calcium chloride dihydrate (BCCD). The spectra are fitted by using the Kurosawa model for the dielectric function. The fits allow the observation of the temperature dependence of the vibrational parameters of the more important polar modes. Particular attention is paid to the lower-frequency polar modes, which are very sensitive to the sequence of phase transitions in this compound. The lower frequencies of the z(yy)x-Raman spectrum, measured between room temperature and T = 20 K, allow a tentative identification of the symmetry of the low-energy modes that become infrared active at lower temperatures. It is shown that these modes correspond very likely to external modes, where the BCCD molecules behave as rigid units. In the ferroelectric phase, the IR spectrum is compatible with the orthorhombic space group . The study of the pyroelectric effect along the [100] direction, in a sample cut as a plate parallel to a natural crystalline face to avoid misorientation, does not reveal any trace of an x-component of the spontaneous polarization, previously reported. This result seems to confirm the absence of intrinsic monoclinic distortions in the ferroelectric phase of BCCD.

Betaine calcium chloride dihydrate is known to exhibit a rich number of commensurate and incommensurate phases (k = δ(T) c*) between a room temperature paraelectric phase (Pnma) and a lower temperature ferroelectric phase (Pn2 1 a). Partial bromination of this compound induces important changes in the phase diagram of the material. This work reports recent results of FIR reflectivity, dielectric dispersion and pyroelectric effect measured on 8% brominated BCCD. In agreement with previous Raman results reported by Schaack and coworkers, the FIR reflectivity (E∥b) spectra (20 cm -1 < ω < 300 cm -1 ) show that the sequence of commensurate and incommensurate phases observed in the pure compound is shifted towards lower temperatures and that the structure remains modulated at lower temperatures (modulation wavenumber δ 1/4 at T = 20 K). The temperature and frequency dependence of the dielectric constants e & and e b , as well as the behaviour of the pyroelectric coefficient λb observed along a sequence of thermal cycles with and without a bias field, indicate a progressive deviation from thermal equilibrium and a subsequent freezing of the structure at low temperatures. The experimental results are discussed within the framework of a phenomenological model based on a Landau-type free energy expansion, previously reported to account for the phase transition sequence observed in the pure crystal under a positive hydrostatic pressure.

The temperature dependence of infrared reflection spectra of betaine phosphate single crystal is reported for polarizations parallel to the a- and b-axes. The spectra were fitted with the factorized form of the dielectric function. A mode assignment is proposed on the basis of a comparison with the spectra of betaine phosphite and deuterated betaine phosphate. Some very asymmetric phonon lines are observed, and the importance of mode couplings is emphasized. A picture of a tendency towards transverse optical mode softening of the low-frequency spectrum upon approaching either side of the phase transition temperature emerges for the polarization parallel to the b-axis, consistent with the peak observed in the temperature dependence of the dielectric constant. On the other hand, the temperature dependence of the ionic effective charges does not display any appreciable discontinuity at the phase transition, contrary to what is observed at the temperature of the transition to the ferroelectric phase of the parent compound betaine phosphite. This is consistent with the very low level of the spontaneous polarization below in betaine phosphate. The similarities of the behaviours with those of the compounds of the KDP family are discussed.

The complex dielectric constant of the orientational glass (SCT) with x = 0.0055 was measured as a function of time at 4.2 K, for frequencies ranging from 1 kHz to 1 MHz, after different thermal histories. Both the in-phase component and the out-of-phase component clearly exhibit aging as shown by the cooling rate dependence of their evolution. Moreover, a weak dependence has been seen for the asymptotic values of both components at very long time. Hence, evidence exists for ergodicity breaking. This is in contrast to what was seen for spin glasses, and similar to what was observed for the series (KLT) of orientational glasses studied previously. However, when temperature jumps are imposed on the SCT sample, the response differs both from that of spin glasses and from that of the KLT series.

A systematic analysis of the dielectric constant as a function of temperature in SrTiO 3 : Ca crystals with Ca content of 0.0020, 0.0032, 0.0055. 0.0058, and 0.0110 shows that the Barrett parameters are clearly modified by the Ca content. We have found for each Ca concentration the temperature below which the contribution of the Ca induced clusters becomes sizeable. The values obtained for the fitted parameters in the Barrett formula allow us to trace a boundary between the low-temperature quantum paraelectric and ferroelectric regimes.

The clear identification of ferroelectric and antiferroelectric phases in liquid crystalline compounds is very important for applications of these materials and for the basic knowledge of the structure of these phases. The use of a macroscopic technique, such as the polarization hysteresis loops, is relatively not expensive, reliable and reveals to be a good method to study many of the characteristics of these phases. The evolution of the coercive field with the frequency, the surface and ionic contributions and the cell thickness influence on the shape of the loops is also considered in this work.