Browsing M.Sc. Physics by Subject "lock-in amplifier"
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High Temperature Method Of Measuring Electrical And Magnetic Properties Of Europium Doped Nickel OxideThe measurement of the magnetic moment of materials as a function of temperature in modern AC or DC magnetometers normally has a limited high temperature range up to 400 K. To overcome this problem one needs to design ovens which can handle high temperatures. The highest Curie temperature observed in materials is in pure Co which is about 1400 K. However, most materials and compounds show Tc below 800 K. My thesis research topic is to study the substitution of Ni ions by rare earth ions in NiO. The NiO is a semiconductor which exhibits antiferromagnetism below 520 K, which makes it suitable for applications; to name a few, rechargeable batteries, and p-type transport conducting lms. In this study, Ni ions were substituted by 2, 5, and 8 percent of Eu ions. The effect of substitution on the semiconducting properties of Ni1-xEuxO was studied as function of temperature from room temperature to 1000 K. To study the magnetic properties and the effect of Eu substitution on the Neel temperature of Ni1-xEuxO we adapted two ovens for high temperature measurements of AC susceptibility by using the ac modulation technique implementing a lock-in ampli er and the DC susceptibility using the SQUID magnetometer. To check the reliability of these two ovens we also examined the ferromagnetic transition temperatures of Bismuth Ferrite samples as function of Co substitutions for Fe.