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Calcium barium niobate (CBN), also like strontium barium niobate (SBN), belongs to the materials family of partially filled tetragonal tungsten bronzes, which show relaxor-type ferroelectric phase transitions and large electro-optic effects. For the first time, it was possible to grow large single crystals of Ca 0.25 Ba 0.75 Nb 2 O 6 (CBN-25) and CBN-28 by using different growing techniques. The successful single crystal growth allowed to investigate several physical properties of the novel phase. Herein, we report on measurements of differential thermal analysis (DTA), wavelength dispersion of the refractive indices, temperature dependence of the birefringence and light absorption. Additionally, results of the single crystal X-ray structure analysis are presented.

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Large single crystals of the polar lithium sulfamate, Li[NH2SO3], were grown from aqueous solution. The crystal structure was determined using single crystal X‐ray diffraction data (space group: Pca21 (Nr. 29), a = 16.253(2) Å, b = 5.0529(3) Å, c = 8.2469(7) , R = 0.019). Precise refractive indices were measured in the wavelength region between 0.36 μm and 1.53 μm. Above λ ≈ 0.85 μm Li[NH2SO3] shows optic uniaxial behaviour. A phase‐matched optical second harmonic generation is not possible. Measurements of temperature dependence of thermal expansion and of main birefringences Δn(i) have given no hints for structural phase transitions in the investigated temperature region (from ‐130 °C to +25 °C).

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