Dielectric response near the permittivity maximum in ( Sr 0.8 Pb 0.2 ) TiO 3 ceramic solid solution Lanthanum doped SrBi 2 Nb 2 O 9 ceramics with the chemical formula SrBi 2−x La x Nb 2 O 9 ͑SBLN͒ ͑x =0-0.5͒ have been prepared through conventional solid state route. X-ray diffraction reveals the shrinkage of unit cell of strontium bismuth niobate with incorporation of La 3+ dopant, having no lone pair electrons. Shifting of Raman phonon modes indicates the reduced rattling space of NbO 6 octahedra with increase in La doping concentration. Further, the softening of lowest frequency phonon mode with increasing x in SBLN shows the transition from ferroelectric to paraelectric at room temperature. The dielectric properties for all the compositions are studied as a function of temperature ͑25 to 500°C͒ over the frequency range of 10 kHz-1 MHz. With increase in lanthanum doping concentration the phase transition becomes diffused and transition temperature gets shifted toward lower temperature. A phase transition from normal ferroelectric to paraelectric has been observed via relaxor-type ferroelectrics with increase in x. The frequency dependence of transition temperature was studied in terms of Vogel-Fulcher relation for SBLN ͑x = 0.4͒.

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SrBi 2 Nb 2 O 9 (SBN) and SrBi 1.9 La 0.1 Nb 2 O 9 (SBLN) have been prepared through conventional solid state route. The crystallographic orientation of the prepared ceramics was investigated using x-ray diffraction. FTIR spectroscopy indicate the growth of single-phase layered perovskite material. The dielectric properties of prepared ceramics are studied as a function of frequency (10 KHz-1 MHz) at different temperatures (25-500 • C). The phase transition temperature of SrBi 2 Nb 2 O 9 ceramic was found to decrease from 420 • C to 395 • C with La (10%) doping. A slight decrease in the value of dc conductivity at 500 • C from 3.82 × 10 −6 to 2.28 × 10 −6 −1 cm −1 was observed with substitution of La at the Bi-site. The power law behavior of ac conductivity is analyzed as a function of frequency at different temperatures.

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In this paper we report a novel method for determining the Planck’s constant experimentally. We have determined the Planck’s constant using light emitting diodes (LEDs) of four different colours (Red, Green, Yellow and Blue) with the aid of a python programming. The LEDs were not provided with a specific wavelength value, and they could have any arbitrary wavelength in their respective colour bands. We determined the wavelengths of the LED lights using a Python program and calculated the value of the Planck’s constant using them. The value obtained was compared with the Planck’s constant value determined using a traditional method being followed in undergraduate labs and its actual value. The relative error while reporting the value of Planck’s constant using traditional method was around 18% which was reduced to 6% by using the method reported in the present study.

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