[Paper Review] Kinetic Parameters analysis of GdAlO$_3$ based on thermoluminescent phenomenon

D. Nolasco-Altamirano, C. S. Romero-Nuñez+7 more|arXiv (Cornell University)|Jun 3, 2024

Luminescence Properties of Advanced MaterialsMaterials Science3 citations

TL;DR

This study analyzes thermoluminescence (TL) kinetic parameters in synthetic GdAlO₃ phosphors using multiple deconvolution methods, with Computing Glow Curve Deconvolution (CGCD) identified as the most effective for resolving overlapping peaks. The results reveal a complex trap distribution with both continuous and discrete components, providing detailed activation energies and frequency factors critical for dosimetry applications.

ABSTRACT

{We herein report on the calculation of thermoluminescence (TL) kinetic parameters determined from the TL emission of synthetic GdAlO3 (GAO) phosphors prepared by the co-precipitation method. The sample, characterized by means of X-ray diffraction with an orthorhombic phase structure (space group Pnma (62), shows complex glow curves consisting of at least four groups of components peaked at 100, 140, 240, and 290 °C where the two lower overlapped temperature peaks are difficult to identify using the $T_M-T_{stop}$. The coexistence of a continuum in the trap distribution (linked to the lower temperature peaks) and a discrete trap system (associated with the components at temperatures higher than 200 °C) can be distinguished. The estimation of the TL kinetic parameters is performed using GlowFit, TLAnal, the spreadsheet Origin, Computing Glow Curve Deconvolution (CGCD), and various heating rate (VHR) methods. However, only CGCD appears as the suitable technique for such purpose since it provides information on the TL physical process supported by mathematical models based on a linear combination of functions related to the First Order Kinetic approach.

Motivation & Objective

• To determine the thermoluminescence (TL) kinetic parameters of synthetic GdAlO₃ phosphors prepared via co-precipitation.
• To investigate the nature of trapping centers in GdAlO₃ by analyzing complex glow curves with overlapping peaks.
• To compare the performance of multiple TL analysis techniques—GlowFit, TLAnal, Origin, VHR, and CGCD—in resolving kinetic parameters.
• To distinguish between continuous and discrete trap distributions based on peak shape and heating rate behavior.
• To provide a comprehensive characterization of TL behavior in GdAlO₃ for potential use in radiation dosimetry.

Proposed method

• Synthesized GdAlO₃ phosphors via co-precipitation and characterized using X-ray diffraction (XRD), confirming an orthorhombic structure (space group Pnma, No. 62).
• Acquired thermoluminescence glow curves under varying heating rates to study kinetic behavior and peak resolution.
• Applied multiple analysis techniques: GlowFit for curve fitting, TLAnal for deconvolution, Origin for data visualization, and VHR for kinetic parameter estimation.
• Employed the Computing Glow Curve Deconvolution (CGCD) method, which uses a linear combination of first-order kinetic functions to model glow curves.
• Used the $T_{ ext{max}} - T_{ ext{stop}}$ method to assess peak behavior and infer trap distribution type (continuous vs. discrete).
• Evaluated the physical consistency of results by comparing activation energies ($E_a$), frequency factors ($s$), and kinetic order ($b$) across methods.

Figure 2: Thermoluminescence glow curves of GdAlO 3 after being exposed to 13.2 Gy beta radiation using different heating rate values (0.5 – 10 K/s).

Experimental results

Research questions

• RQ1 What are the kinetic parameters (activation energy, frequency factor, kinetic order) of the thermoluminescence glow peaks in GdAlO₃?
• RQ2 How do different deconvolution methods (GlowFit, TLAnal, Origin, VHR, CGCD) compare in resolving overlapping TL peaks in GdAlO₃?
• RQ3 What is the nature of the trap distribution in GdAlO₃—continuous or discrete—and how is it reflected in the glow curve shape?
• RQ4 To what extent do heating rate variations affect the peak position and shape, and how does this inform the underlying trapping mechanism?
• RQ5 Which method provides the most accurate and physically consistent description of the TL process in GdAlO₃ with complex glow curves?

Key findings

• The TL glow curve of GdAlO₃ exhibits at least four components peaking at 100 °C, 140 °C, 240 °C, and 290 °C, with the first two peaks overlapping and difficult to resolve using the $T_{ ext{max}} - T_{ ext{stop}}$ method.
• A continuous distribution of traps is associated with the lower-temperature peaks (100 °C and 140 °C), while discrete trap systems dominate the higher-temperature peaks (240 °C and 290 °C).
• Among the tested methods, CGCD provided the most accurate and physically consistent resolution of kinetic parameters, supported by first-order kinetic models.
• The $T_{ ext{max}} - T_{ ext{stop}}$ method indicated a quasi-continuous trap distribution, with peak positions increasing at higher stopping temperatures.
• The VHR and peak shape methods showed sensitivity to overlapping peaks, leading to potential misinterpretation, especially for the first two components.
• The study confirms that a multi-method approach enhances the reliability of kinetic parameter estimation, with CGCD being optimal for complex, overlapping glow curves in GdAlO₃.

Figure 3: X-ray diffraction pattern of GdAlO 3 powders. The diffraction peaks correspond to an orthorhombic crystal structure in the Pnma (62) space group, consistent with JPCDS Card No. 48-0310. The narrow and sharp (132) and (231) peaks indicate good crystallization characteristics.