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The term ‘glass’ has a precise scientific meaning: a glass, or a substance in the glassy or vitreous state, is a material, formed by cooling down from the normal liquid state, which has shown no discontinuous change (such as crystallization or separation into more than one phase) at any temperature, but has become more or less rigid through a progressive increase in its viscosity. In common usage, the term ‘glass’ refers to a class of versatile materials of great practical usefulness, with a number of very characteristic properties which are typically hard and brittle solids, lustrous and often optically transparent. Glass is one type of amorphous solid material which also shows property of softening progressively and continuously when heated. The term is usually applied to inorganic solids and not to plastics or other organics. Glasses do not have crystalline (non-crystalline) internal structure. Its molecules have a disordered arrangement, but there is enough cohesion to produce rigidity. Majority of glass seen in everyday life is transparent, but glass can also be translucent or opaque. In science, however, the term glass is usually defined in a much wider sense, including every solid that possesses a non-crystalline (i.e. amorphous) structure and that exhibits a glass transition when heated towards the liquid state. The term ‘glass’ was developed in the late Roman Empire. It was in the Roman glassmaking center at Trier, now in modern Germany, that the late-Latin term glesum originated, probably from a Germanic word for a transparent, lustrous substance. Glasses can be made of quite different classes of materials. Glassy state, which is a universal property of supercooled liquids if they are cooled rapidly enough, is regarded as the fourth state of matter. The physics of glass is the science of the glassy or amorphous state of matter as seen from an atomic or molecular point of view. The mysterious glass transition phenomenon, which connects the liquid and glassy more...

The term ‘glass’ has a precise scientific meaning: a glass, or a substance in the glassy or vitreous state, is a material, formed by cooling down from the normal liquid state, which has shown no discontinuous change (such as crystallization or separation into more than one phase) at any temperature, but has become more or less rigid through a progressive increase in its viscosity. In common usage, the term ‘glass’ refers to a class of versatile materials of great practical usefulness, with a number of very characteristic properties which are typically hard and brittle solids, lustrous and often optically transparent. Glass is one type of amorphous solid material which also shows property of softening progressively and continuously when heated. The term is usually applied to inorganic solids and not to plastics or other organics. Glasses do not have crystalline (non-crystalline) internal structure. Its molecules have a disordered arrangement, but there is enough cohesion to produce rigidity. Majority of glass seen in everyday life is transparent, but glass can also be translucent or opaque. In science, however, the term glass is usually defined in a much wider sense, including every solid that possesses a non-crystalline (i.e. amorphous) structure and that exhibits a glass transition when heated towards the liquid state. The term ‘glass’ was developed in the late Roman Empire. It was in the Roman glassmaking center at Trier, now in modern Germany, that the late-Latin term glesum originated, probably from a Germanic word for a transparent, lustrous substance. Glasses can be made of quite different classes of materials. Glassy state, which is a universal property of supercooled liquids if they are cooled rapidly enough, is regarded as the fourth state of matter. The physics of glass is the science of the glassy or amorphous state of matter as seen from an atomic or molecular point of view. The mysterious glass transition phenomenon, which connects the liquid and glassy more...

A series of binary tellurite glass (TeO2)x(B2O3)1-x with x= 0.6-0.8 have been calculated using the bond compression model. The atomic ring size of the network has been obtained from the ring deformation model. The composition dependence of these parameters showed the elasticity and hence the respond of this glass system is influence by the chemical nature of tellurite dioxide composition. Variation of the estimated atomic ring size with ratio of the bond compression model Kbc to experimental Ke bulk modulus was studied to obtain more information about the structure of the glass. The result showed that the small value or the large value of Kbc/Ke are attributed to the very close (small ringed) three-dimensional network of these glasses. more...

Polycrystalline of (La1-xNdx)0.5Ba0.5MnO3 with x = 0, 1/6, 1/3, ½, 2/3, 5/6 and 1 has been prepared using solid state reaction. The effect of substituting neodymium at Lasite on magnetoresistance (MR) effect has been investigated. The doped samples are calcined at 900oC for 12 hours, pelletized and sintered at 1300oC for 24 hours. The magnetoresistance (MR) was measured at a magnetic field of H ≤ 1T at 90K, 100K, 150K, 200K, 250K, 270K and 300K. Overall, MR drops slowly when temperature rises. All doping concentration gives small variation range (~8.97% to ~63.49%). The highest MR value of 63.49 % was observed at 150K for sample of x = 1.0. The metal-insulator transition temperature, TP shifted towards lower temperatures as Nd doping increased, Tp followed by decreasing of the activation energy (Ea), which are 254, 244, 218, 198, 146, 130 and 114 K for the bulks with x = 0, 1/6, 1/3, ½, 2/3, 5/6 and 1, respectively. In the semi-conducting portion, activation energy (Ea) decreases as the doping concentration increases. more...

Polycrystalline of (La1-xNdx)0.5Ba0.5MnO3 with x = 0, 1/6, 1/3, ½, 2/3, 5/6 and 1 has been prepared using solid state reaction. The effect of substituting neodymium at Lasite on magnetoresistance (MR) effect has been investigated. The doped samples are calcined at 900oC for 12 hours, pelletized and sintered at 1300oC for 24 hours. The magnetoresistance (MR) was measured at a magnetic field of H ≤ 1T at 90K, 100K, 150K, 200K, 250K, 270K and 300K. Overall, MR drops slowly when temperature rises. All doping concentration gives small variation range (~8.97% to ~63.49%). The highest MR value of 63.49 % was observed at 150K for sample of x = 1.0. The metal-insulator transition temperature, TP shifted towards lower temperatures as Nd doping increased, Tp followed by decreasing of the activation energy (Ea), which are 254, 244, 218, 198, 146, 130 and 114 K for the bulks with x = 0, 1/6, 1/3, ½, 2/3, 5/6 and 1, respectively. In the semi-conducting portion, activation energy (Ea) decreases as the doping concentration increases. more...

A series of binary tellurite glass (TeO2)x(B2O3)1-x with x= 0.6-0.8 have been calculated using the bond compression model. The atomic ring size of the network has been obtained from the ring deformation model. The composition dependence of these parameters showed the elasticity and hence the respond of this glass system is influence by the chemical nature of tellurite dioxide composition. Variation of the estimated atomic ring size with ratio of the bond compression model Kbc to experimental Ke bulk modulus was studied to obtain more information about the structure of the glass. The result showed that the small value or the large value of Kbc/Ke are attributed to the very close (small ringed) three-dimensional network of these glasses. more...