Brushite [CaHPO4·2H2O] or calcium hydrogen phosphate dihydrate (CHPD) also known as urinary crystal is a stable form of calcium phosphate. The brushite crystals were grown by single and double diffusion techniques in agar-agar gel at room temperature. Effects of different growth parameters were discussed in single diffusion and double diffusion techniques. Good quality star, needle, platy, rectangular, and prismatic shaped crystals in single diffusion and nuclei with dendritic growth were obtained in double diffusion. These grown nuclei were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). SEM has shown the different morphologies of crystals; FTIR has confirmed the presence of functional groups; crystalline nature was supported by XRD, whereas the TGA indicates total 24.68% loss in weight and formation of stable calcium pyrophosphate (Ca2P2O7) at 500°C.

The phosphate mineral struvite is basically formed in urinary tracks and kidney. One of the analogous compounds of struvite is potassium magnesium phosphate hexahydrate (KMgPO 4 •6H 2 O), known as struvite-k crystal and found in animal urinary calculi. In the present investigation, struvite-k crystals were grown by single diffusion and double diffusion techniques in agar gelmedium. The grown crystals were analyzed by optical microscopy, scanning electron microscopy (SEM), fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), energy dispersive X-ray analysis (EDXA) and thermogravimetric analysis (TGA). Optical microscopy and SEM exhibited the different morphologies. The FTIR spectra revealed the presence of water molecules, stretching and bending vibrations of phosphate (PO4) ions. However the powder XRD results from the crystalline nature. Elemental composition in the crystal was obtained by EDXA, while 36.89% weight loss of water molecules is observed in TGA study.

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Thermal glow curves of KBr: Tl phosphors were investigated after irradiation with ultraviolet light or X-rays at room temperature. It was found that the specimens exhibited a single glow peak in the temperature range of 340–370 K, the position of the maximum of which depended on the history of the sample. Present work included the effects on the thermoluminescent characteristics of the phosphor when subjected to various thermal and/or mechanical treatments. It is proposed that the Tl+ ion-anion vacancy pair situated in the perfect region of the lattice is responsible for the peak at 370 K. Shift in the peak position to lower temperature side is attributed to the Tl+ ion-anion vacancy pair in the distorted region of the lattice, the distortion being caused by the vacancy cluster in the neighbourhood of the pair.