Shape-controlled crystal growth of Sr3NbGa3Si2O14 and Sr3TaGa3Si2O14 piezoelectric single crystal by micro-pulling-down method
We have grown the shape-controlled Sr<inf>3</inf>NbGa<inf>3</inf>Si<inf>2</inf>O<inf>14</inf> (SNGS) and Sr<inf>3</inf>TaGa<inf>3</inf>Si<inf>2</inf>O<inf>14</inf> (STGS) langasite-type crystals by the μ-PD method. Columnar-shaped SNGS and STGS crystals were grown using the Pt-Rh crucible with a columnar die in 3 mm diameter. Grown crystals indicated high transparency and approximately 3 mm diameter. Chemical phases of grown crystals were identified as a single phase of langasite-type structure. The lattice parameters of grown crystals were almost consistent with those of crystals grown by Czochralski (Cz) method. In the X-ray rocking curve measurements, the grown crystals indicated equivalent crystallinity to the crystal grown by Cz method.
Optical and scintillation properties of Sr3BGa3Si2O14 (B = Nb, Ta) single crystals
Abstract Optical and scintillation properties of Sr 3 NbGa 3 Si 2 O 14 [SNGS] and Sr 3 TaGa 3 Si 2 O 14 [STGS] single crystals with the langasite-type crystal structure were investigated as a novel scintillator materials. In the transmittance spectra of the SNGS and STGS polished specimens, absorption peaks around 380 and 505 nm were observed and the absorptions are considered to be attributable to the excess oxygen in the crystals. An emission peak around 420 nm was observed in the X-ray radioluminescence spectrum of the SNGS crystal. On the other hand, there was an emission peak around 335 nm in the X-ray radioluminescence spectrum of the STGS crystal.
Development of polyamide curable modified epoxy novolac resins with improved adhesion and chemical resistance
Purpose – To prepare modified epoxy resins from resorcinol, cresol and phenol for improved adhesion and chemical resistance. To evaluate the properties of such modified epoxy resins.Design/methodology/approach – Epoxy novolac resins (ENRs) were synthesised by condensing epichlorohydrin with novolacs based on different types of substituted phenols for improving adhesion and chemical resistance. Various compositions were made by incorporating different proportions of polyamide resin. The chemical and adhesive strengths of the conventional epoxy and the modified epoxy resins were characterised.Findings – The modified ENR using substituted phenols showed significant enhancement of chemical and adhesive strengths over the conventional DGEBA resin. The modified ENR had an increased number of glycidyl groups (thus increased functionality) of resin, which was responsible for improved chemical and adhesive strengths over the conventional DGEBA resin.Research limitations/implications – The EPN resins used in the pr...