Electronic, magnetic and thermal properties of Pb₂₋x AxCrO₅ (A = K or La)

Lead chromium oxide is a photoconductive dielectric material tha t has great potential of being used as a room temperature photodetector. In this research, we made ceramic pellets of this compound as well as potassium doped compound Pb2-xKxCr05, where x=O, 0.05, 0.125. We also investigate the properties of the lanthanum doped sample whose chemical formula is Pb1.85Lao.15Cr05' The electronic, magnetic and thermal properties of these materials have been studied. Magnetization measurements of the Pb2Cr05 sample indicate a transition at about 310 K, while for the lanthanum doped sample the transition temperature is at about 295 K indicating a paramagnetic behavior. However, the potassium doped samples are showing the transition from paramagnetic state to diamagnetic state at different temperatures for different amounts of potassium atoms present in the sample. We have studied resistivity as a function of temperature in different gas environments from 300 K to 900 K. The resistivity measurement of the parent sample indicates a conducting to insulating transition at about 300 K and upon increasing the temperature further, above 450 K the sample becomes an ionic conductor. As temperature increases a decrease in resistance is observed in the lanthanum/potassium doped samples. Using Differential Scanning Calorimetry experiment an endothermic peak is observed for the Pb2Cr05 and lanthanum/potassium doped samples at about 285 K.

Glacial stratigraphy and micromorphology of the Pine Point Pb-­‐Zn mining district, Northwest Territories

This investigation aims to gain a better understanding of the glacial history of the Pine Point Mining district, Northwest Territories, by examining the sedimentological properties of the glacial sediments including, geochemical analysis, heavy mineral concentrate analysis, clast macro-­‐fabrics, pebble lithologies, and micromorphological investigation. Four till units were identified, and three were associated with identified erosional bedrock features and streamlined landforms in the area, indicating a minimum of three ice flow directions. Sedimentological properties suggest that these units were all Type-­B tectomict/mélange till, emplaced as part of a soft subglacial deformable bed. The lack of ice-­‐marginal advance and retreat sequences within the studied till, suggests the Middle Wisconsinan Laurentide Ice margin was likely north and west of the Pine Point area, as opposed to along the margin of the Canadian Shield and Western Sedimentary Basin where it has been suggested to have existed.

PB #2B

Dark brown sediment that appears almost black. This may be due to organic content. Clasts are well dispersed and range from small to medium. The clast shape ranges from angular to sub-rounded. Lineations can be seen throughout the sample. Grain crushing can also be seen in minor amounts.

PB #7F TvDT

Dark brown, fine grained sediment. Mainly structure less with organic content. A few faint water escape structures can also be seen.

PB 3 (Y) KZ

Dark brown sediment, almost black due to organic material. Mainly structure-less with a few well dispersed clasts. Grains range from small to medium in size and sub-angular to rounded in shape.

PB 18 TVD

Dark brown sediment with organic material present throughout. The clasts are mainly small. Lineations are abundant throughout the sample.

PB 99 4B

Light brown sediment with clasts ranging from small to medium in size. The clast shape ranges from sub-angular to sub-rounded. Lineations are abundant throughout the sample. A few water escape structures can also be seen.

PB 1C(z)

Dark brown sediment with well dispersed clasts. The clasts are mainly small and range from sub-angular to rounded in shape. This sample is mainly structure-less but does contain lineations.

TvD PB #61

Brown sediment with well dispersed clasts ranging from small to large. Clast shape ranges from angular to sub-rounded. Lineations can be seen throughout the sample. There is one small patch of another domain present. This domain is light brown, and contains clasts that are clustered together. Grain crushing is abundant in this domain, as well as in other areas of the sample.

TVD #9 PB

Dark brown sediment (almost black), with a few clasts that are very well dispersed. The clasts range from small to medium in size. The clast shape ranges from sub-angular to rounded. The sample is mainly structureless. There are a few inclusions of a lighter domain. This domain contains more clasts than the darker one.