Tb Ceramics Research Articles

Fabrication of Gd2O2S:Tb scintillation ceramics using water-bath method: The influence of initial reaction temperature

Gd2O2S:Tb nanopowders were synthesized in hot water-bath with the equal mole ratio of Gd2O3 and H2SO4 as raw materials. The influence of initial bathing temperature of Gd2O3 and H2SO4, which was defined as initial temperature, on the properties of precursors and powders was investigated. The precursors and Gd2O2S:Tb powders showed a layered structure, and all the reduced powders exhibit a pure Gd2O2S phase. With the increase of the initial temperature, the size and thickness of the flakes in the precursors and Gd2O2S:Tb powders increased. Using the obtained powders as starting materials, Gd2O2S:Tb scintillation ceramics were successfully fabricated by vacuum pre-sintering at 1250 °C for 3 h, followed by HIP post-treatment at 1450 °C for 3 h. The Gd2O2S:Tb ceramics from the powders prepared at lower initial temperature show a rapid densification rate during pre-sintering. The Gd2O2S:Tb ceramics from powders synthesized at 7 °C show the highest optical transmittance and XEL intensity, and the total transmittance of the ceramics with the thickness of 1.0 mm is 25.5% at 545 nm. The microstructures of the Gd2O2S:Tb ceramics from powders synthesized at different initial temperatures were also studied.

Fabrication of Gd2O2S:Tb scintillation ceramics from the uniformly doped nanopowder

Abstract Single-phase 2Gd2O3·(Gd,Tb)2(SO4)3·nH2O precursor with strong crystallinity was synthesized by the water-bath method through optimizing the introducing method of Tb3+ doping, where Tb3+ was introduced from Tb(NO3)3. The formation process and phase evolution of the precursor were analyzed in detail. Compared with the conventional method of introducing Tb3+ via Tb4O7, the inhomogeneous doping caused by the appearance of 2Tb2O3·(Gd,Tb)2(SO4)3·nH2O in the precursor was avoided. Pure Gd2O2S:Tb nanopowders with layered structure were obtained after calcination in flowing H2-Ar. The Gd2O2S:Tb powder prepared with Tb(NO3)3 has higher XEL intensity than that with Tb4O7. Using the synthesized powders as starting material, Gd2O2S:Tb scintillation ceramics with high relative density (over 99% of the theoretical value) were fabricated by vacuum pre-sintering and HIP post-treatment in an argon atmosphere. The influences of the introducing method of Tb3+ doping on the microstructure, photoluminescence and X-ray excited luminescence of the Gd2O2S:Tb ceramics were studied. The ceramic sample prepared with Tb(NO3)3 has better luminescence properties due to the homogeneous doping in the ceramics. Temperature-dependent XEL measurements imply that the green emission of the ceramic sample is always dominant with the increase of temperature from 77 K to 340 K, attributed to the cross-relaxation between 5D3 and 5D4 levels of Tb3+.

Photoluminescence, scintillation, and dosimetric properties of Ce-codoped MgF2:Tb ceramics

Photoluminescence (PL), scintillation, and dosimetric properties of the Ce-codoped MgF2:Tb ceramics were evaluated. The Ce-codoped MgF2:Tb ceramics showed some PL emission peaks ascribed to the 4f–4f transitions of the Tb3+ ion and the 5d–4f transitions of the Ce3+ ion. It was confirmed that the emission wavelength of Ce3+ overlapped with the excitation wavelength of Tb3+, and the quantum yield was improved by codoping of Tb and Ce. In addition, the thermally-stimulated luminescence (TSL) glow curves mainly had the glow peak at 245 °C, and TSL spectra showed emission peaks due to the Tb3+ ion. TSL dose response functions were also evaluated, and the dynamic range with linear responses was from 0.01 to 1000 mGy.

Investigation of structural, ferroelectric and magnetic properties of iron doped tungsten bronze multiferroic ceramics

Ba5CaTi2-xFexNb8O30 (x = 0.00, 0.02, 0.04, 0.06 and 0.08) Tungsten Bronze Ceramics were synthesized by conventional solid-state method. In this paper, the effect of Fe substitution in BCTN (Barium Calcium Titanium Niobate) on micro-structural, Raman, ferroelectric and ferromagnetic properties are discussed. The X-ray diffraction (XRD) result reveals the formation of a single-phase tetragonal structure of the synthesized samples. The grain size and morphology of the sample were confirmed by using a Scanning electron microscope (SEM). The P–E loop exhibits the ferroelectric nature of TB ceramics. The substitution of Fe ions improves the magnetic behavior of synthesized material.

Evaluation of dosimetric properties of Li-codoped MgF2:Tb ceramics

Li-codoped MgF2:Tb ceramics with different Li concentrations (0.01, 0.1, 1, and 3 mol%) were prepared by the spark plasma sintering method, and photoluminescence (PL), scintillation, and dosimetric properties were investigated. Sharp peaks due to 4-4 f transitions of Tb3+ ion were observed in all of PL, scintillation, and thermally-stimulated luminescence (TSL). TSL glow curves confirmed that the TSL intensity was increased by Li-codoping without an increase of QY values. Especially, the TSL intensity was the highest in 1% Li-codoped MgF2:Tb, which was approximately 2.2 times larger than that of MgF2 doped with only Tb. Moreover, It was confirmed that the TSL responses of the 0.01, 0.1 and 1% Li-codoped MgF2:Tb ceramics were very sensitive to irradiation dose and showed a good linearity from 0.01 to 1000 mGy.

Fabrication and properties of Gd2O2S:Tb scintillation ceramics for the high-resolution neutron imaging

Terbium doped gadolinium oxysulfide (GOS:Tb) ceramics were successfully fabricated by pre-sintering in vacuum and HIP post-treatment in Ar atmosphere. Ceramic densification in vacuum and HIP was discussed in the detail mainly by relative density and FESEM characterizations. The fabricated GOS:Tb ceramics were translucent with 0.5 mm thickness after HIP post-treatment. Optical and scintillation properties of GOS:Tb ceramics were also investigated. Temperature-dependent X-ray excited spectra were recorded using a homemade XEL spectrometer. Neutron scintillation light output was also measured in China Spallation Neutron Source (CSNS). The light output was measured to be about 284 photons per neutron with different thicknesses of GOS:Tb ceramics.

Gd2O2S:Tb scintillation ceramics fabricated from high sinterability nanopowders via hydrogen reduction

Crystallized Gd2(OH)4SO4·nH2O precursor was synthesized in hot water bath using oxide powders and concentrated sulfuric acid as raw materials. Calcining the precursor in air produced the intermediate product Gd2O2SO4 and Gd2O2S powders with high phase purity was obtained by hydrogen reduction. The Gd2O2S powders showed layered structure and severe agglomeration with SBET = 6.321 m2/g. Using this powders, a two-step sintering method comprised of pre-sintering in vacuum and hot isostatic pressing post-treatment was introduced for the fabrication of Gd2O2S:Tb ceramics. The relative density increased from 95.7% in pre-sintered body to 99.2% in final ceramics. Densification processes and chemical homogeneity of the ceramics were discussed. Photoluminescence and X-ray excited luminescence of the final ceramics demonstrated a bright green emission centered at 545 nm due to the 5D4 -7F5 transition of Tb3+.

Effect of reducing annealing on the microstructure and thermoelectric properties of La–Bi co-doped SrTiO3 ceramics

Sr1−xLaxTiO3 (SLTB) ceramics were fabricated by conventional solid state reaction method. SLTB ceramics were sintered in air, argon and nitrogen atmospheres and then annealed in argon and graphite (Ar + C) atmosphere. The effect of reducing annealing atmosphere on the microstructure and thermoelectric properties of La–Bi co-doped SrTiO3 ceramics was investigated. The results showed that the S0.9L0.1TB ceramics sintered in argon have the lowest resistivity (5.6 × 104 Ω cm). And the resistivity of S0.9L0.1TB ceramics annealed in Ar + C environment at 1450 °C for 16 h decreased significantly (6–7 orders of magnitude). The Seebeck coefficient is negative with the increasing absolute value at elevated temperature. The thermal conductivity decreased with the temperature increased. The power factor and electrical conductivity increase first and then decrease with increasing temperatures. S0.9L0.1TB ceramics have a maximum value of Seebeck coefficient (−255 μV/K) at 1073 K and the figure of merit ZT 1073K = 0.269.

Lu2O3:Tb,Hf storage phosphor

Lu2O3:Tb,Hf ceramics containing 0.1% of Tb and 0–1.5% of Hf were prepared in reducing atmosphere at 1700 °C and their thermoluminescence properties were systematically studied. For comparison Tb,Ca co-doped specimen was also fabricated and investigated. The Tb,Hf ceramics shows basically a single TL band located around 180 °C as found with heating rate of 15 °C/min. Ceramics singly doped with Tb show complex TL glow curves indicating the presence of traps of very different depths. On the other hand Tb,Ca co-doping is beneficial for the development of shallow traps with the main TL band around 70 °C. Hence, the aliovalent impurities, Ca2+ and Hf4+, strongly influenced the traps structure in Lu2O3:Tb ceramics, each of them in its own specific way. Isothermal decay of Lu2O3:Tb,Hf at 185 °C was recorded and its shape suggest that multiple hole trapping occurs in the Lu2O3:Tb,Hf ceramics. Due to the different traps depths the Lu2O3:Tb,Hf ceramics possess properties typical for storage phosphors, while Lu2O3:Tb,Ca is a persistent luminescent material rather.