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In this work, the effect of ZrO2-doping on the microstructure evolution and phase change of Tb3Al5O12 (TAG) ceramics has been investigated systematically. Except for the transformation of Zr4+–Zr3+, a novel phenomenon is discovered in the final stage of sintering that a second phase of ZrO2 is discharged to the surface of samples at the sintering temperature higher than 1550 °C, which is accompanied with a largely promoted grain growth at the same time. The discharge behavior is considered to contribute to the enhanced optical quality of TAG ceramics for the decreasing residual impurity in grain boundaries.

(Tb1-xTmx)3Al5O12 transparent ceramics were successfully fabricated using solid state reaction and vacuum sintering. Influences of Tm3+ ion doping on the phase compositions, microstructure and magneto-optical characteristics of the prepared ceramics were investigated systematically. The results show that the increase in Tm3+ ion concentrations has no distinct effect on the crystal structure and average grain size of TAG ceramics. The undoped TAG transparent ceramic exhibits the best optical transmission and the optical transmittance decreases with the increase of Tm3+ doping concentrations due to the increased scattering centers. It is found that the Verdet constant of the samples increases with increasing the Tm3+ doping concentrations, which is benefit for improving the magnetic performance. The Verdet constant of 0.16 at% Tm3+-doped TAG ceramic is 189.5 rad T−1 m−1 at 633 nm wavelength, which is 41% higher than that of commercial TGG crystal.

TAG transparent ceramics with different Tb4O7 additive contents were successfully fabricated using solid state reaction and vacuum sintering. The samples (T1-T5) added with 0-0.3 wt% Tb4O7 exhibit high transparency in the visible and near infrared regions. It was found that adding 0.1–0.2 wt% Tb4O7 was in favor of eliminating pores and optimizing magneto-optical properties and the ceramic added with 0.1 wt% Tb4O7 (T2) possesses the highest transmittance, which reached 80.32% at 1064 nm. The TAP phase was detected by XRD and appeared in the microstructure of sample T7 with added 0.8 wt% Tb4O7 content, which inhibited grain boundary migration and deteriorated the optical quality of TAG transparent ceramics. The Verdet constant increases slightly with a small increase in the amount of Tb4O7 addition and the value of sample T5 added with 0.3 wt% Tb4O7 is 177.5rad/(T·m), which is 32% higher than that of the commercially TGG crystal.

Y3Al5O12:Ce3+/Mn2+/Si4+ phosphor ceramics were fabricated by solid state reaction. Red emission is obtained, which is attributed to the Mn2+:4T1→6A1 spin-forbidden transition under the excitation of 450 nm via the efficient energy transfer from Ce3+ to Mn2+.The green emission (535 nm) originating from Ce3+ and the orange emission (587 nm) from Mn2+ ions were observed. Mn2+ ions are more inclined to occupy Al3+ octahedral sites and the Si4+ ions locate in the Al3+ tetrahedral sites and their co-doping is for charge compensation. The red emission component in Ce3+/Mn2+/Si4+ doping YAG phosphor ceramics is significant for obtaining warm white lighting upon increasing Mn2+ concentration under 450 nm excitation. White light emitting diodes were successfully constructed by combining the fabricated ceramics with the GaN blue chips.

In this paper, the chemical composition of Y3Al5O12 was modified to Ce:(MgyY2.99-y) (Al5-ySiy)O12 (MYASG) and Ce:Y2.99(MgxAl5-2xSix)O12 (YMASG) through the Mg2+-Si4+ substitution for Y3+-Al3+ and Al3+-Al3+, respectively. The increasing (decreasing) lattice constants, downward (upward) shift of Raman peaks and shorter (longer) luminescence lifetime were investigated in YMASG (MYASG) through the Rietveld analysis, Raman spectra and luminescent decay spectra. Moreover, a massive red-shift emission peak was observed in YMASG, from 537 nm to 577 nm. While for MYASG, the maximum emission peak of Ce3+ locates at 552 nm and the emission peaks remain unchanged even further increasing Mg2+-Si4+. The distinct red-shift properties can be ascribed to the different crystal structure due to the Mg2+ doping in different coordinate sites and are clarified by the configuration coordinate model. The broad color area from yellow to orange region in the color coordinates diagram was achieved which proves the great potential application of YMASG ceramic phosphors in the warm white light illumination.

Al2O3-Ce:Tb3Al5O12(TAG) composite ceramics have been synthesized by solid-state vacuum sintering for the application of high efficiency warm white light illumination. The microstructures and fluorescent properties were investigated systematically. Through the introduction of Al2O3 particles, the luminous efficiency (LE) of Ce:TAG ceramics based LED can be largely promoted by ~40%. When the molar ratio of Al2O3/Ce:TAG is 0.4, the photoelectric properties can be modified by the scattering from both Al2O3 and residual pores. Moreover, a high color-rendering index(CRI) of 63 and a low color correlated temperature(CCT) of 3580 K can also be obtained at the same time. The results indicate that Al2O3-Ce:TAG composite ceramics are very promising candidates for the application of high-quality white-lighting.

The variation of strength of fly ash geopolymer under different alkali activator modulus is studied. In this paper, three samples with modulus of alkali initiator 1.0, 2.0, 3.0 were prepared by laboratory test, and the unconfined compressive strength, SEM scanning and XRD analysis were conducted. Results show that the strength of the fly ash geopolymer negative correlation with alkali excitation agent module, with higher modulus alkali excitation agent, the strength of the polymer decreased obviously. From the micro perspective, the lower modulus of the sample of the microstructure appear more dense, gelling material produce more obvious at the same time. From the part of XRD, different modulus of the sample composition are same basically.

The nominal composition of Al2O3-Ce:Y3Mg1.8Al1.4Si1.8O12 (A-Ce:YMASG) ceramic phosphors was fabricated by the vacuum sintering technique. The introduction of Al2O3 as a second phase partially enters the crystal lattice, which was confirmed by the composition changing of the samples through x-ray diffraction measurement. An impurity phase of Y4MgSi3O13 was observed in Ce:YMASG and disappeared with the introduction of Al2O3 at the concentration of 10 wt. %. When the content of Al2O3 increased to 30 and 50 wt. %, the second phase of Al2O3 was measured with actual weight ratios of 7.72 and 20.55 wt. %, respectively. The third phase of MgAl2O4 was found with the further addition of Al2O3at 70 wt. %; the weight ratios of Ce:YMASG, Al2O3, and MgAl2O4 were 68.756, 18.457, and 12.787 wt. %, respectively. The luminescent characters of the samples were measured by the photoluminescence spectra and electroluminescent spectra. With the increase of Al2O3 from 0 to 30 wt. %, the emission wavelength of Ce3+ plummeted from 610 to 552 nm, and the luminous efficacy of the samples increased from 35 to 65 lm/W.

(Tb,Gd)3Al5O12: Ce3+ (Ce: TGAG) transparent phosphor ceramics with different concentrations of Gd-doping were fabricated for the first time through a solid state reaction. The maximum emission peak of Ce3+ shifts from 550 nm to 570 nm in Ce:TGAG and the emission intensity of Ce3+ was also greatly increased. With an increasing red component in fluorescence spectrum, a low color correlated temperature (CCT) of 3681 K and a high color-rendering index (CRI) of 74.7 were obtained in the packed LED device based on InGaN chips and Ce:TGAG ceramics at the Gd-doping concentration of 30%, which indicates the great potential of Ce:TGAG ceramics in the application of warm white light illumination.

In view of the high cost of the existing grouting materials, and at the same time the industrial production of a large number of fly ash, slag and other industrial waste can’t be effectively used. In this paper, the properties of fly ash slag cement with different ratios were studied through laboratory tests. Results show that the cement content in given conditions, with the increase of dosage of fly ash, initial setting and final setting time of cement paste with slow growth, the fluidity is growing, but the stone rate has obvious drop, on the compressive strength, the higher the slag content, is the early compressive strength, the greater the and the higher the dosage of fly ash, the late strength of cement paste were higher. This kind of grouting material has good working performance, can guarantee the project construction needs at the same time save cost, protect the environment.